const std = @import("std");
const zfin = @import("../root.zig");
const srf = @import("srf");
const history = @import("../history.zig");
pub const fmt = @import("../format.zig");

// ── Default CLI colors (match TUI default Monokai theme) ─────
pub const CLR_POSITIVE = [3]u8{ 0x7f, 0xd8, 0x8f }; // gains (TUI .positive)
pub const CLR_NEGATIVE = [3]u8{ 0xe0, 0x6c, 0x75 }; // losses (TUI .negative)
pub const CLR_MUTED = [3]u8{ 0x80, 0x80, 0x80 }; // dim/secondary text (TUI .text_muted)
pub const CLR_HEADER = [3]u8{ 0x9d, 0x7c, 0xd8 }; // section headers (TUI .accent)
pub const CLR_ACCENT = [3]u8{ 0x89, 0xb4, 0xfa }; // info highlights, bar fills (TUI .bar_fill)
pub const CLR_WARNING = [3]u8{ 0xe5, 0xc0, 0x7b }; // stale/manual price indicator (TUI .warning)

// ── ANSI color helpers ───────────────────────────────────────

pub fn setFg(out: *std.Io.Writer, c: bool, rgb: [3]u8) !void {
    if (c) try fmt.ansiSetFg(out, rgb[0], rgb[1], rgb[2]);
}

pub fn setBold(out: *std.Io.Writer, c: bool) !void {
    if (c) try fmt.ansiBold(out);
}

pub fn reset(out: *std.Io.Writer, c: bool) !void {
    if (c) try fmt.ansiReset(out);
}

pub fn setGainLoss(out: *std.Io.Writer, c: bool, value: f64) !void {
    if (c) {
        if (value >= 0)
            try fmt.ansiSetFg(out, CLR_POSITIVE[0], CLR_POSITIVE[1], CLR_POSITIVE[2])
        else
            try fmt.ansiSetFg(out, CLR_NEGATIVE[0], CLR_NEGATIVE[1], CLR_NEGATIVE[2]);
    }
}

/// Map a semantic StyleIntent to CLI ANSI color.
pub fn setStyleIntent(out: *std.Io.Writer, c: bool, intent: fmt.StyleIntent) !void {
    if (!c) return;
    switch (intent) {
        .normal => try reset(out, c),
        .muted => try setFg(out, c, CLR_MUTED),
        .positive => try setFg(out, c, CLR_POSITIVE),
        .negative => try setFg(out, c, CLR_NEGATIVE),
        .warning => try setFg(out, c, CLR_WARNING),
    }
}

// ── Styled print helpers ─────────────────────────────────────
//
// Collapse the common `setX; print(...); reset` triple into a single
// call. Every renderer used to spell out all three steps; these
// helpers keep the "set → write → reset" boundary intact while
// cutting line count roughly in half at the call site.

/// Set a foreground color, print a formatted string, reset.
pub fn printFg(
    out: *std.Io.Writer,
    c: bool,
    rgb: [3]u8,
    comptime fmt_str: []const u8,
    args: anytype,
) !void {
    try setFg(out, c, rgb);
    try out.print(fmt_str, args);
    try reset(out, c);
}

/// Set a bold attribute, print a formatted string, reset.
pub fn printBold(
    out: *std.Io.Writer,
    c: bool,
    comptime fmt_str: []const u8,
    args: anytype,
) !void {
    try setBold(out, c);
    try out.print(fmt_str, args);
    try reset(out, c);
}

/// Set a semantic-intent color, print a formatted string, reset.
pub fn printIntent(
    out: *std.Io.Writer,
    c: bool,
    intent: fmt.StyleIntent,
    comptime fmt_str: []const u8,
    args: anytype,
) !void {
    try setStyleIntent(out, c, intent);
    try out.print(fmt_str, args);
    try reset(out, c);
}

/// Set a sign-aware gain/loss color, print a formatted string, reset.
pub fn printGainLoss(
    out: *std.Io.Writer,
    c: bool,
    value: f64,
    comptime fmt_str: []const u8,
    args: anytype,
) !void {
    try setGainLoss(out, c, value);
    try out.print(fmt_str, args);
    try reset(out, c);
}

// ── Stderr helpers ───────────────────────────────────────────

pub fn stderrPrint(msg: []const u8) !void {
    var buf: [1024]u8 = undefined;
    var writer = std.fs.File.stderr().writer(&buf);
    const out = &writer.interface;
    try out.writeAll(msg);
    try out.flush();
}

/// Print progress line to stderr: "  [N/M] SYMBOL (status)"
pub fn stderrProgress(symbol: []const u8, status: []const u8, current: usize, total: usize, color: bool) !void {
    var buf: [256]u8 = undefined;
    var writer = std.fs.File.stderr().writer(&buf);
    const out = &writer.interface;
    if (color) try fmt.ansiSetFg(out, CLR_MUTED[0], CLR_MUTED[1], CLR_MUTED[2]);
    try out.print("  [{d}/{d}] ", .{ current, total });
    if (color) try fmt.ansiReset(out);
    try out.print("{s}", .{symbol});
    if (color) try fmt.ansiSetFg(out, CLR_MUTED[0], CLR_MUTED[1], CLR_MUTED[2]);
    try out.print("{s}\n", .{status});
    if (color) try fmt.ansiReset(out);
    try out.flush();
}

/// Print rate-limit wait message to stderr
pub fn stderrRateLimitWait(wait_seconds: u64, color: bool) !void {
    var buf: [256]u8 = undefined;
    var writer = std.fs.File.stderr().writer(&buf);
    const out = &writer.interface;
    if (color) try fmt.ansiSetFg(out, CLR_NEGATIVE[0], CLR_NEGATIVE[1], CLR_NEGATIVE[2]);
    if (wait_seconds >= 60) {
        const mins = wait_seconds / 60;
        const secs = wait_seconds % 60;
        if (secs > 0) {
            try out.print("  (rate limit -- waiting {d}m {d}s)\n", .{ mins, secs });
        } else {
            try out.print("  (rate limit -- waiting {d}m)\n", .{mins});
        }
    } else {
        try out.print("  (rate limit -- waiting {d}s)\n", .{wait_seconds});
    }
    if (color) try fmt.ansiReset(out);
    try out.flush();
}

/// Progress callback for loadPrices that prints to stderr.
/// Shared between the CLI portfolio command and TUI pre-fetch.
pub const LoadProgress = struct {
    svc: *zfin.DataService,
    color: bool,
    /// Offset added to index for display (e.g. stock count when loading watch symbols).
    index_offset: usize,
    /// Grand total across all loadPrices calls (stocks + watch).
    grand_total: usize,

    fn onProgress(ctx: *anyopaque, index: usize, _: usize, symbol: []const u8, status: zfin.DataService.SymbolStatus) void {
        const self: *LoadProgress = @ptrCast(@alignCast(ctx));
        const display_idx = self.index_offset + index + 1;
        switch (status) {
            .fetching => {
                // Show rate-limit wait before the fetch
                if (self.svc.estimateWaitSeconds()) |w| {
                    if (w > 0) stderrRateLimitWait(w, self.color) catch {};
                }
                stderrProgress(symbol, " (fetching)", display_idx, self.grand_total, self.color) catch {};
            },
            .cached => {
                stderrProgress(symbol, " (cached)", display_idx, self.grand_total, self.color) catch {};
            },
            .fetched => {
                // Already showed "(fetching)" — no extra line needed
            },
            .failed_used_stale => {
                stderrProgress(symbol, " FAILED (using cached)", display_idx, self.grand_total, self.color) catch {};
            },
            .failed => {
                stderrProgress(symbol, " FAILED", display_idx, self.grand_total, self.color) catch {};
            },
        }
    }

    pub fn callback(self: *LoadProgress) zfin.DataService.ProgressCallback {
        return .{
            .context = @ptrCast(self),
            .on_progress = onProgress,
        };
    }
};

/// Aggregate progress callback for parallel loading operations.
/// Displays a single updating line with progress bar.
pub const AggregateProgress = struct {
    color: bool,
    last_phase: ?zfin.DataService.AggregateProgressCallback.Phase = null,
    last_completed: usize = 0,

    fn onProgress(ctx: *anyopaque, completed: usize, total: usize, phase: zfin.DataService.AggregateProgressCallback.Phase) void {
        const self: *AggregateProgress = @ptrCast(@alignCast(ctx));

        const phase_changed = self.last_phase == null or self.last_phase.? != phase;
        self.last_phase = phase;

        var buf: [256]u8 = undefined;
        var writer = std.fs.File.stderr().writer(&buf);
        const w = &writer.interface;

        switch (phase) {
            .cache_check => {},
            .server_sync => {
                if (completed != self.last_completed) {
                    if (self.color) fmt.ansiSetFg(w, CLR_MUTED[0], CLR_MUTED[1], CLR_MUTED[2]) catch {};
                    w.print("  Syncing from server... [{d}/{d}]\n", .{ completed, total }) catch {};
                    if (self.color) fmt.ansiReset(w) catch {};
                    w.flush() catch {};
                    self.last_completed = completed;
                }
            },
            .provider_fetch => {
                if (phase_changed) {
                    if (self.color) fmt.ansiSetFg(w, CLR_MUTED[0], CLR_MUTED[1], CLR_MUTED[2]) catch {};
                    w.print("  Synced {d} from server, fetching remaining from providers...\n", .{completed}) catch {};
                    if (self.color) fmt.ansiReset(w) catch {};
                    w.flush() catch {};
                }
            },
            .complete => {},
        }
    }

    pub fn callback(self: *AggregateProgress) zfin.DataService.AggregateProgressCallback {
        return .{
            .context = @ptrCast(self),
            .on_progress = onProgress,
        };
    }
};

/// Unified price loading for both CLI and TUI.
/// Handles parallel server sync when ZFIN_SERVER is configured,
/// with sequential provider fallback for failures.
pub fn loadPortfolioPrices(
    svc: *zfin.DataService,
    portfolio_syms: ?[]const []const u8,
    watch_syms: []const []const u8,
    force_refresh: bool,
    color: bool,
) zfin.DataService.LoadAllResult {
    var aggregate = AggregateProgress{ .color = color };
    var symbol_progress = LoadProgress{
        .svc = svc,
        .color = color,
        .index_offset = 0,
        .grand_total = (if (portfolio_syms) |ps| ps.len else 0) + watch_syms.len,
    };

    const result = svc.loadAllPrices(
        portfolio_syms,
        watch_syms,
        .{ .force_refresh = force_refresh, .color = color },
        aggregate.callback(),
        symbol_progress.callback(),
    );

    // Print summary
    const total = symbol_progress.grand_total;
    const from_cache = result.cached_count;
    const from_server = result.server_synced_count;
    const from_provider = result.provider_fetched_count;
    const failed = result.failed_count;
    const stale = result.stale_count;

    var buf: [256]u8 = undefined;
    var writer = std.fs.File.stderr().writer(&buf);
    const out = &writer.interface;

    if (from_cache == total) {
        if (color) fmt.ansiSetFg(out, CLR_MUTED[0], CLR_MUTED[1], CLR_MUTED[2]) catch {};
        out.print("  Loaded {d} symbols from cache\n", .{total}) catch {};
        if (color) fmt.ansiReset(out) catch {};
    } else if (failed > 0) {
        if (color) fmt.ansiSetFg(out, CLR_MUTED[0], CLR_MUTED[1], CLR_MUTED[2]) catch {};
        if (stale > 0) {
            out.print("  Loaded {d} symbols ({d} cached, {d} server, {d} provider, {d} failed — {d} using stale)\n", .{ total, from_cache, from_server, from_provider, failed, stale }) catch {};
        } else {
            out.print("  Loaded {d} symbols ({d} cached, {d} server, {d} provider, {d} failed)\n", .{ total, from_cache, from_server, from_provider, failed }) catch {};
        }
        if (color) fmt.ansiReset(out) catch {};
    } else {
        if (color) fmt.ansiSetFg(out, CLR_MUTED[0], CLR_MUTED[1], CLR_MUTED[2]) catch {};
        if (from_server > 0 and from_provider > 0) {
            out.print("  Loaded {d} symbols ({d} cached, {d} server, {d} provider)\n", .{ total, from_cache, from_server, from_provider }) catch {};
        } else if (from_server > 0) {
            out.print("  Loaded {d} symbols ({d} cached, {d} server)\n", .{ total, from_cache, from_server }) catch {};
        } else {
            out.print("  Loaded {d} symbols ({d} cached, {d} fetched)\n", .{ total, from_cache, from_provider }) catch {};
        }
        if (color) fmt.ansiReset(out) catch {};
    }
    out.flush() catch {};

    return result;
}

// ── Portfolio loading ────────────────────────────────────────

/// Result of loading and parsing a portfolio file. Caller must call deinit().
pub const LoadedPortfolio = struct {
    file_data: []const u8,
    portfolio: zfin.Portfolio,
    positions: []const zfin.Position,
    syms: []const []const u8,

    pub fn deinit(self: *LoadedPortfolio, allocator: std.mem.Allocator) void {
        allocator.free(self.syms);
        allocator.free(self.positions);
        self.portfolio.deinit();
        allocator.free(self.file_data);
    }
};

/// Read, deserialize, and extract positions + symbols from a portfolio file.
/// Returns null (with stderr message) on read/parse errors.
pub fn loadPortfolio(allocator: std.mem.Allocator, file_path: []const u8) ?LoadedPortfolio {
    const file_data = std.fs.cwd().readFileAlloc(allocator, file_path, 10 * 1024 * 1024) catch {
        stderrPrint("Error: Cannot read portfolio file\n") catch {};
        return null;
    };

    var portfolio = zfin.cache.deserializePortfolio(allocator, file_data) catch {
        allocator.free(file_data);
        stderrPrint("Error: Cannot parse portfolio file\n") catch {};
        return null;
    };

    const positions = portfolio.positions(allocator) catch {
        portfolio.deinit();
        allocator.free(file_data);
        stderrPrint("Error: Cannot compute positions\n") catch {};
        return null;
    };

    const syms = portfolio.stockSymbols(allocator) catch {
        allocator.free(positions);
        portfolio.deinit();
        allocator.free(file_data);
        stderrPrint("Error: Cannot get stock symbols\n") catch {};
        return null;
    };

    return .{
        .file_data = file_data,
        .portfolio = portfolio,
        .positions = positions,
        .syms = syms,
    };
}

// ── Portfolio data pipeline ──────────────────────────────────

/// Result of the shared portfolio data pipeline. Caller must call deinit().
pub const PortfolioData = struct {
    summary: zfin.valuation.PortfolioSummary,
    candle_map: std.StringHashMap([]const zfin.Candle),
    snapshots: ?[6]zfin.valuation.HistoricalSnapshot,

    pub fn deinit(self: *PortfolioData, allocator: std.mem.Allocator) void {
        self.summary.deinit(allocator);
        var it = self.candle_map.valueIterator();
        while (it.next()) |v| allocator.free(v.*);
        self.candle_map.deinit();
    }
};

/// Build portfolio summary, candle map, and historical snapshots from
/// pre-populated prices. Shared between CLI `portfolio` command, TUI
/// `loadPortfolioData`, and TUI `reloadPortfolioFile`.
///
/// Callers are responsible for populating `prices` (via network fetch,
/// cache read, or pre-fetched map) before calling this.
///
/// Returns error.NoAllocations if the summary produces no positions
/// (e.g. no cached prices available).
pub fn buildPortfolioData(
    allocator: std.mem.Allocator,
    portfolio: zfin.Portfolio,
    positions: []const zfin.Position,
    syms: []const []const u8,
    prices: *std.StringHashMap(f64),
    svc: *zfin.DataService,
) !PortfolioData {
    var manual_price_set = try zfin.valuation.buildFallbackPrices(allocator, portfolio.lots, positions, prices);
    defer manual_price_set.deinit();

    var summary = zfin.valuation.portfolioSummary(allocator, portfolio, positions, prices.*, manual_price_set) catch
        return error.SummaryFailed;
    errdefer summary.deinit(allocator);

    if (summary.allocations.len == 0) {
        summary.deinit(allocator);
        return error.NoAllocations;
    }

    var candle_map = std.StringHashMap([]const zfin.Candle).init(allocator);
    errdefer {
        var it = candle_map.valueIterator();
        while (it.next()) |v| allocator.free(v.*);
        candle_map.deinit();
    }
    for (syms) |sym| {
        if (svc.getCachedCandles(sym)) |cs| {
            // cs.data is owned by svc.allocator(), which matches the
            // caller's `allocator` in practice (they're wired to the
            // same root). Store the raw slice; PortfolioData.deinit
            // below frees via the caller's allocator.
            candle_map.put(sym, cs.data) catch {};
        }
    }

    const snapshots = zfin.valuation.computeHistoricalSnapshots(
        fmt.todayDate(),
        positions,
        prices.*,
        candle_map,
    );

    return .{
        .summary = summary,
        .candle_map = candle_map,
        .snapshots = snapshots,
    };
}

// ── As-of date parsing (shared by CLI --as-of and TUI date popup) ──

pub const AsOfParseError = error{
    InvalidFormat,
    EmptyUnit,
    UnknownUnit,
    ZeroQuantity,
};

/// Parse a user-supplied as-of string into an optional `Date`.
///
/// Return value: `null` means live (today's portfolio); a non-null
/// `Date` is the resolved absolute date the caller should look up in
/// the snapshot directory. Relative forms (`1M`, `3Y`, ...) are
/// converted here — callers receive the resolved date, not the
/// shortcut string.
///
/// Accepted forms (case-insensitive for keywords and unit letters):
///   - ""             → null      (empty = live)
///   - "live" / "now" → null
///   - "YYYY-MM-DD"   → explicit date
///   - "N[WMQY]"      → today − N units; calendar arithmetic
///
/// Units:
///   - W = weeks (subtract N * 7 days)
///   - M = months (calendar; Mar 31 - 1M → Feb 28/29)
///   - Q = quarters (3 months)
///   - Y = years (calendar; Feb 29 - 1Y → Feb 28)
///
/// `today` is injected rather than read from the clock so tests are
/// deterministic. In production call sites this is `fmt.todayDate()`.
///
/// Fractional forms like `1.5Y` are not accepted — keep the parser
/// small and unambiguous.
pub fn parseAsOfDate(input: []const u8, today: zfin.Date) AsOfParseError!?zfin.Date {
    const s = std.mem.trim(u8, input, " \t\r\n");

    if (s.len == 0) return null;

    // Keyword forms.
    if (std.ascii.eqlIgnoreCase(s, "live") or std.ascii.eqlIgnoreCase(s, "now")) {
        return null;
    }

    // Explicit YYYY-MM-DD.
    if (s.len == 10 and s[4] == '-' and s[7] == '-') {
        return zfin.Date.parse(s) catch error.InvalidFormat;
    }

    // Relative: N[WMQY].
    // Digits prefix then a single unit letter.
    var i: usize = 0;
    while (i < s.len and s[i] >= '0' and s[i] <= '9') : (i += 1) {}
    if (i == 0) return error.InvalidFormat;
    if (i >= s.len) return error.EmptyUnit;
    if (i + 1 != s.len) return error.InvalidFormat;

    // u16 is the widest quantity that all downstream ops (subtractYears,
    // subtractMonths, addDays) accept without further narrowing.
    const n = std.fmt.parseInt(u16, s[0..i], 10) catch return error.InvalidFormat;
    if (n == 0) return error.ZeroQuantity;

    const unit = std.ascii.toLower(s[i]);
    return switch (unit) {
        'w' => today.addDays(-@as(i32, n) * 7),
        'm' => today.subtractMonths(n),
        'q' => today.subtractMonths(n * 3),
        'y' => today.subtractYears(n),
        else => error.UnknownUnit,
    };
}

/// Human-readable explanation of why a given string failed to parse.
/// Caller-owned buffer; returns a slice. No trailing newline — the
/// caller is responsible for formatting the surrounding message.
pub fn fmtAsOfParseError(buf: []u8, input: []const u8, err: AsOfParseError) []const u8 {
    return switch (err) {
        error.InvalidFormat => std.fmt.bufPrint(buf, "Invalid as-of value: {s}. Expected YYYY-MM-DD, N[WMQY] (e.g. 1M, 3Q, 2Y), or 'live'.", .{input}) catch input,
        error.EmptyUnit => std.fmt.bufPrint(buf, "As-of value {s} is missing a unit. Expected one of W, M, Q, Y.", .{input}) catch input,
        error.UnknownUnit => std.fmt.bufPrint(buf, "As-of value {s} has an unknown unit. Expected one of W (weeks), M (months), Q (quarters), Y (years).", .{input}) catch input,
        error.ZeroQuantity => std.fmt.bufPrint(buf, "As-of quantity must be at least 1 (got {s}).", .{input}) catch input,
    };
}

/// Parse a user-facing date argument that must resolve to a concrete
/// absolute date — no "live"/"now"/empty. Accepts the same grammar
/// as `parseAsOfDate` (`YYYY-MM-DD` or relative shortcuts like `1W`,
/// `1M`, `1Q`, `1Y`, case-insensitive) minus the null-producing
/// inputs. Used by commands where a date-argument bound to a
/// specific date makes sense but "live" doesn't — e.g. `compare`'s
/// positional args, `history --since`/`--until`, `snapshot --as-of`.
///
/// `today` is injected for test determinism. Production callers pass
/// `fmt.todayDate()`.
pub const RequiredDateError = AsOfParseError || error{LiveNotAllowed};

pub fn parseRequiredDate(input: []const u8, today: zfin.Date) RequiredDateError!zfin.Date {
    const parsed = try parseAsOfDate(input, today);
    return parsed orelse error.LiveNotAllowed;
}

/// Convenience pattern: parse a required date, print a helpful error
/// to stderr if it fails, and map every failure mode to a single
/// `error.InvalidDate`. Callers get a uniform error, stderr gets a
/// message that tells the user exactly what grammar is accepted
/// including the relative-shortcut syntax.
///
/// `today` is injected for test determinism.
pub fn parseRequiredDateOrStderr(
    input: []const u8,
    today: zfin.Date,
    arg_label: []const u8,
) error{InvalidDate}!zfin.Date {
    return parseRequiredDate(input, today) catch |err| {
        var ebuf: [256]u8 = undefined;
        const msg = switch (err) {
            error.LiveNotAllowed => std.fmt.bufPrint(
                &ebuf,
                "Error: {s} must be a concrete date, not 'live'/'now'.\n",
                .{arg_label},
            ) catch "Error: invalid date\n",
            else => |e| blk: {
                var inner: [256]u8 = undefined;
                const detail = fmtAsOfParseError(&inner, input, e);
                break :blk std.fmt.bufPrint(
                    &ebuf,
                    "Error: {s}: {s} (expected YYYY-MM-DD or a relative shortcut like 1W/1M/1Q/1Y)\n",
                    .{ arg_label, detail },
                ) catch "Error: invalid date\n";
            },
        };
        stderrPrint(msg) catch {};
        return error.InvalidDate;
    };
}

// ── Snapshot resolution (CLI) ────────────────────────────────

/// Snap a requested snapshot date to the nearest earlier snapshot
/// that exists in `hist_dir`, printing CLI-friendly stderr messages
/// when resolution fails.
///
/// Thin wrapper over `history.resolveSnapshotDate` that bundles the
/// "no snapshot at or before X, earliest available is Y" hint that
/// both `projections --as-of` and `compare` surface to the user.
/// Returns the full `ResolvedSnapshot` so callers can distinguish
/// exact vs. inexact matches (compare uses this to print a muted
/// "snapped to …" notice, projections uses `actual != requested` to
/// drive the header).
///
/// On `error.NoSnapshotAtOrBefore` the stderr messages are emitted
/// and the error is propagated verbatim; callers typically map it to
/// their own command-level error (`error.NoSnapshot`,
/// `error.SnapshotNotFound`, etc.). Other errors propagate without a
/// stderr write — they indicate filesystem-level failures the caller
/// should surface itself.
///
/// Uses `arena` for the intermediate message strings; pass a
/// short-lived arena.
pub fn resolveSnapshotOrExplain(
    arena: std.mem.Allocator,
    hist_dir: []const u8,
    requested: zfin.Date,
) !history.ResolvedSnapshot {
    return history.resolveSnapshotDate(arena, hist_dir, requested) catch |err| switch (err) {
        error.NoSnapshotAtOrBefore => {
            var req_buf: [10]u8 = undefined;
            const req_str = requested.format(&req_buf);
            const msg = std.fmt.allocPrint(arena, "No snapshot at or before {s}.\n", .{req_str}) catch "No snapshot at or before the requested date.\n";
            stderrPrint(msg) catch {};
            // Second look at the nearest table for the "later
            // available" hint. Cheap (filesystem scan, same dir).
            const nearest = history.findNearestSnapshot(hist_dir, requested) catch {
                stderrPrint("No snapshots in history/ — run `zfin snapshot` to create one.\n") catch {};
                return err;
            };
            if (nearest.later) |later| {
                var later_buf: [10]u8 = undefined;
                const later_str = later.format(&later_buf);
                const later_msg = std.fmt.allocPrint(arena, "Earliest available: {s} (later than requested).\n", .{later_str}) catch "A later snapshot exists but was not used.\n";
                stderrPrint(later_msg) catch {};
            } else {
                stderrPrint("No snapshots in history/ — run `zfin snapshot` to create one.\n") catch {};
            }
            return err;
        },
        else => |e| return e,
    };
}

// ── Watchlist loading ────────────────────────────────────────

/// Load a watchlist SRF file containing symbol records.
/// Returns owned symbol strings. Returns null if file missing or empty.
pub fn loadWatchlist(allocator: std.mem.Allocator, path: []const u8) ?[][]const u8 {
    const file_data = std.fs.cwd().readFileAlloc(allocator, path, 1024 * 1024) catch return null;
    defer allocator.free(file_data);

    const WatchEntry = struct { symbol: []const u8 };

    var reader = std.Io.Reader.fixed(file_data);
    var it = srf.iterator(&reader, allocator, .{ .alloc_strings = false }) catch return null;
    defer it.deinit();

    var syms: std.ArrayList([]const u8) = .empty;
    while (it.next() catch null) |fields| {
        const entry = fields.to(WatchEntry) catch continue;
        const duped = allocator.dupe(u8, entry.symbol) catch continue;
        syms.append(allocator, duped) catch {
            allocator.free(duped);
            continue;
        };
    }
    if (syms.items.len == 0) {
        syms.deinit(allocator);
        return null;
    }
    return syms.toOwnedSlice(allocator) catch null;
}

pub fn freeWatchlist(allocator: std.mem.Allocator, watchlist: ?[][]const u8) void {
    if (watchlist) |wl| {
        for (wl) |sym| allocator.free(sym);
        allocator.free(wl);
    }
}

// ── Tests ────────────────────────────────────────────────────

test "setFg emits ANSI when color enabled" {
    var buf: [256]u8 = undefined;
    var w: std.Io.Writer = .fixed(&buf);
    try setFg(&w, true, CLR_POSITIVE);
    const out = w.buffered();
    // Should contain ESC[ sequence with RGB values
    try std.testing.expect(out.len > 0);
    try std.testing.expect(std.mem.startsWith(u8, out, "\x1b["));
}

test "setFg is no-op when color disabled" {
    var buf: [256]u8 = undefined;
    var w: std.Io.Writer = .fixed(&buf);
    try setFg(&w, false, CLR_POSITIVE);
    try std.testing.expectEqual(@as(usize, 0), w.buffered().len);
}

test "setBold emits ANSI when color enabled" {
    var buf: [256]u8 = undefined;
    var w: std.Io.Writer = .fixed(&buf);
    try setBold(&w, true);
    const out = w.buffered();
    try std.testing.expect(out.len > 0);
    try std.testing.expect(std.mem.startsWith(u8, out, "\x1b["));
}

test "setBold is no-op when color disabled" {
    var buf: [256]u8 = undefined;
    var w: std.Io.Writer = .fixed(&buf);
    try setBold(&w, false);
    try std.testing.expectEqual(@as(usize, 0), w.buffered().len);
}

test "reset emits ANSI when color enabled" {
    var buf: [256]u8 = undefined;
    var w: std.Io.Writer = .fixed(&buf);
    try reset(&w, true);
    const out = w.buffered();
    try std.testing.expect(out.len > 0);
    try std.testing.expect(std.mem.indexOf(u8, out, "\x1b[") != null);
}

test "reset is no-op when color disabled" {
    var buf: [256]u8 = undefined;
    var w: std.Io.Writer = .fixed(&buf);
    try reset(&w, false);
    try std.testing.expectEqual(@as(usize, 0), w.buffered().len);
}

test "setGainLoss uses positive color for gains" {
    var buf: [256]u8 = undefined;
    var w: std.Io.Writer = .fixed(&buf);
    try setGainLoss(&w, true, 10.0);
    const out = w.buffered();
    try std.testing.expect(out.len > 0);
    // Should contain the positive green color RGB
    try std.testing.expect(std.mem.indexOf(u8, out, "127") != null);
}

test "setGainLoss uses negative color for losses" {
    var buf: [256]u8 = undefined;
    var w: std.Io.Writer = .fixed(&buf);
    try setGainLoss(&w, true, -5.0);
    const out = w.buffered();
    try std.testing.expect(out.len > 0);
    // Should contain the negative red color RGB
    try std.testing.expect(std.mem.indexOf(u8, out, "224") != null);
}

test "setGainLoss is no-op when color disabled" {
    var buf: [256]u8 = undefined;
    var w: std.Io.Writer = .fixed(&buf);
    try setGainLoss(&w, false, 10.0);
    try std.testing.expectEqual(@as(usize, 0), w.buffered().len);
}

test "setGainLoss treats zero as positive" {
    var buf: [256]u8 = undefined;
    var w: std.Io.Writer = .fixed(&buf);
    try setGainLoss(&w, true, 0.0);
    const out = w.buffered();
    // Should use positive (green) color for zero
    try std.testing.expect(std.mem.indexOf(u8, out, "127") != null);
}

// ── parseAsOfDate tests ─────────────────────────────────────

test "parseAsOfDate: empty string is live" {
    const today = zfin.Date.fromYmd(2026, 4, 2);
    const r = try parseAsOfDate("", today);
    try std.testing.expect(r == null);
}

test "parseAsOfDate: whitespace-only is live" {
    const today = zfin.Date.fromYmd(2026, 4, 2);
    const r = try parseAsOfDate("   \t\n", today);
    try std.testing.expect(r == null);
}

test "parseAsOfDate: literal 'live' and 'now' (case-insensitive)" {
    const today = zfin.Date.fromYmd(2026, 4, 2);
    try std.testing.expect((try parseAsOfDate("live", today)) == null);
    try std.testing.expect((try parseAsOfDate("LIVE", today)) == null);
    try std.testing.expect((try parseAsOfDate("now", today)) == null);
    try std.testing.expect((try parseAsOfDate("Now", today)) == null);
}

test "parseAsOfDate: explicit YYYY-MM-DD" {
    const today = zfin.Date.fromYmd(2026, 4, 2);
    const r = try parseAsOfDate("2026-03-13", today);
    try std.testing.expect(r != null);
    try std.testing.expect(r.?.eql(zfin.Date.fromYmd(2026, 3, 13)));
}

test "parseAsOfDate: weeks subtracts 7*N days" {
    const today = zfin.Date.fromYmd(2026, 4, 2);
    const r = try parseAsOfDate("2W", today);
    // 2026-04-02 - 14 days = 2026-03-19
    try std.testing.expect(r.?.eql(zfin.Date.fromYmd(2026, 3, 19)));
}

test "parseAsOfDate: months uses calendar arithmetic" {
    const today = zfin.Date.fromYmd(2026, 4, 2);
    const r = try parseAsOfDate("1M", today);
    try std.testing.expect(r.?.eql(zfin.Date.fromYmd(2026, 3, 2)));
}

test "parseAsOfDate: month-end clamping" {
    // 2026-03-31 - 1 month = 2026-02-28 (non-leap)
    const today = zfin.Date.fromYmd(2026, 3, 31);
    const r = try parseAsOfDate("1M", today);
    try std.testing.expect(r.?.eql(zfin.Date.fromYmd(2026, 2, 28)));
}

test "parseAsOfDate: quarter = 3 months" {
    const today = zfin.Date.fromYmd(2026, 4, 2);
    const r = try parseAsOfDate("1Q", today);
    try std.testing.expect(r.?.eql(zfin.Date.fromYmd(2026, 1, 2)));
    const r2 = try parseAsOfDate("2Q", today);
    try std.testing.expect(r2.?.eql(zfin.Date.fromYmd(2025, 10, 2)));
}

test "parseAsOfDate: years uses calendar arithmetic" {
    const today = zfin.Date.fromYmd(2026, 4, 2);
    const r = try parseAsOfDate("3Y", today);
    try std.testing.expect(r.?.eql(zfin.Date.fromYmd(2023, 4, 2)));
}

test "parseAsOfDate: leap year clamping via years" {
    const today = zfin.Date.fromYmd(2024, 2, 29);
    const r = try parseAsOfDate("1Y", today);
    try std.testing.expect(r.?.eql(zfin.Date.fromYmd(2023, 2, 28)));
}

test "parseAsOfDate: unit letter is case-insensitive" {
    const today = zfin.Date.fromYmd(2026, 4, 2);
    const r_lower = try parseAsOfDate("1m", today);
    const r_upper = try parseAsOfDate("1M", today);
    try std.testing.expect(r_lower.?.eql(r_upper.?));
}

test "parseAsOfDate: invalid date format" {
    const today = zfin.Date.fromYmd(2026, 4, 2);
    try std.testing.expectError(error.InvalidFormat, parseAsOfDate("2026/03/13", today));
    // Digits-only with no unit falls through to the relative-form parser.
    // It's technically 8 digits with no unit letter, so EmptyUnit is correct.
    try std.testing.expectError(error.EmptyUnit, parseAsOfDate("20260313", today));
}

test "parseAsOfDate: missing unit" {
    const today = zfin.Date.fromYmd(2026, 4, 2);
    try std.testing.expectError(error.EmptyUnit, parseAsOfDate("3", today));
}

test "parseAsOfDate: unknown unit" {
    const today = zfin.Date.fromYmd(2026, 4, 2);
    try std.testing.expectError(error.UnknownUnit, parseAsOfDate("3X", today));
    try std.testing.expectError(error.UnknownUnit, parseAsOfDate("3D", today));
}

test "parseAsOfDate: zero quantity rejected" {
    const today = zfin.Date.fromYmd(2026, 4, 2);
    try std.testing.expectError(error.ZeroQuantity, parseAsOfDate("0M", today));
}

test "parseAsOfDate: quantity that overflows u16 is InvalidFormat" {
    // 70000 doesn't fit in u16; previously rejected via an arbitrary cap.
    // Now the underlying parseInt call rejects it as a format error.
    const today = zfin.Date.fromYmd(2026, 4, 2);
    try std.testing.expectError(error.InvalidFormat, parseAsOfDate("70000Y", today));
}

test "parseAsOfDate: large-but-valid quantity accepted" {
    // 100Y is silly but parses fine — no arbitrary cap.
    const today = zfin.Date.fromYmd(2026, 4, 2);
    const r = try parseAsOfDate("100Y", today);
    try std.testing.expect(r.?.eql(zfin.Date.fromYmd(1926, 4, 2)));
}

test "parseAsOfDate: garbage after digits" {
    const today = zfin.Date.fromYmd(2026, 4, 2);
    try std.testing.expectError(error.InvalidFormat, parseAsOfDate("3MM", today));
    try std.testing.expectError(error.InvalidFormat, parseAsOfDate("3 M", today));
}

test "parseAsOfDate: garbage before digits" {
    const today = zfin.Date.fromYmd(2026, 4, 2);
    try std.testing.expectError(error.InvalidFormat, parseAsOfDate("x3M", today));
}

test "fmtAsOfParseError: mentions the input and hint" {
    var buf: [256]u8 = undefined;
    const msg = fmtAsOfParseError(&buf, "2026/03/13", error.InvalidFormat);
    try std.testing.expect(std.mem.indexOf(u8, msg, "2026/03/13") != null);
    try std.testing.expect(std.mem.indexOf(u8, msg, "YYYY-MM-DD") != null);
}

test "fmtAsOfParseError: no trailing newline" {
    var buf: [256]u8 = undefined;
    const msg = fmtAsOfParseError(&buf, "bad", error.InvalidFormat);
    try std.testing.expect(msg.len > 0);
    try std.testing.expect(msg[msg.len - 1] != '\n');
}