//! `zfin snapshot` — write a daily portfolio snapshot to `history/`.
//!
//! Flow:
//!   1. Locate portfolio.srf via `config.resolveUserFile` (or -p).
//!   2. Derive `history/` dir as `dirname(portfolio.srf)/history/`.
//!   3. Load portfolio + prices (via `cli.loadPortfolioPrices`, TTL-driven).
//!   4. Compute `as_of_date` from cached candle dates of held non-MM
//!      stock symbols.
//!   5. If `history/<as_of_date>-portfolio.srf` already exists and
//!      --force wasn't passed, skip (exit 0, stderr message).
//!   6. Build the snapshot records and write them atomically.
//!
//! The output format is discriminated SRF: every record starts with
//! `kind::<meta|total|tax_type|account|lot>`. Readers demux on that
//! field. See finance/README.md for the full schema.

const std = @import("std");
const srf = @import("srf");
const zfin = @import("../root.zig");
const cli = @import("common.zig");
const atomic = @import("../atomic.zig");
const version = @import("../version.zig");
const portfolio_mod = @import("../models/portfolio.zig");
const Date = @import("../models/date.zig").Date;

pub const SnapshotError = error{
    PortfolioEmpty,
    WriteFailed,
};

// ── Entry point ──────────────────────────────────────────────

/// Run the snapshot command.
///
/// `args` is the slice after `zfin snapshot`. Accepted flags:
///   --force           overwrite existing snapshot for as_of_date
///   --out <path>      override output path (skips the default derivation)
///   --dry-run         compute + print, do not write
///
/// Exit semantics:
///   0 on success (including duplicate-skip)
///   non-zero on any error
pub fn run(
    allocator: std.mem.Allocator,
    svc: *zfin.DataService,
    portfolio_path: []const u8,
    args: []const []const u8,
    color: bool,
    out: *std.Io.Writer,
) !void {
    // Parse flags.
    var force = false;
    var dry_run = false;
    var out_override: ?[]const u8 = null;
    var i: usize = 0;
    while (i < args.len) : (i += 1) {
        const a = args[i];
        if (std.mem.eql(u8, a, "--force")) {
            force = true;
        } else if (std.mem.eql(u8, a, "--dry-run")) {
            dry_run = true;
        } else if (std.mem.eql(u8, a, "--out")) {
            i += 1;
            if (i >= args.len) {
                try cli.stderrPrint("Error: --out requires a path argument\n");
                return error.UnexpectedArg;
            }
            out_override = args[i];
        } else {
            try cli.stderrPrint("Error: unknown argument to 'snapshot': ");
            try cli.stderrPrint(a);
            try cli.stderrPrint("\n");
            return error.UnexpectedArg;
        }
    }

    // Load portfolio.
    const pf_data = std.fs.cwd().readFileAlloc(allocator, portfolio_path, 10 * 1024 * 1024) catch |err| {
        try cli.stderrPrint("Error reading portfolio file: ");
        try cli.stderrPrint(@errorName(err));
        try cli.stderrPrint("\n");
        return err;
    };
    defer allocator.free(pf_data);

    var portfolio = zfin.cache.deserializePortfolio(allocator, pf_data) catch {
        try cli.stderrPrint("Error parsing portfolio file.\n");
        return error.WriteFailed;
    };
    defer portfolio.deinit();

    if (portfolio.lots.len == 0) {
        try cli.stderrPrint("Portfolio is empty; nothing to snapshot.\n");
        return SnapshotError.PortfolioEmpty;
    }

    // Fetch prices via the shared TTL-driven loader.
    const syms = try portfolio.stockSymbols(allocator);
    defer allocator.free(syms);

    var prices = std.StringHashMap(f64).init(allocator);
    defer prices.deinit();

    if (syms.len > 0) {
        var load_result = cli.loadPortfolioPrices(svc, syms, &.{}, false, color);
        defer load_result.deinit();
        var it = load_result.prices.iterator();
        while (it.next()) |entry| {
            try prices.put(entry.key_ptr.*, entry.value_ptr.*);
        }
    }

    // Manual `price::` overrides from portfolio.srf still win.
    for (portfolio.lots) |lot| {
        if (lot.price) |p| {
            if (!prices.contains(lot.priceSymbol())) {
                try prices.put(lot.priceSymbol(), p * lot.price_ratio);
            }
        }
    }

    // Compute as_of_date from the cached candle dates of held non-MM
    // stock symbols. MM symbols are excluded because their quote dates
    // are often weeks stale (dollar impact is nil, but they'd pollute
    // the mode calculation).
    const qdates = try collectQuoteDates(allocator, svc, syms);
    defer allocator.free(qdates.dates);
    const as_of = computeAsOfDate(qdates.dates) orelse Date.fromEpoch(std.time.timestamp());

    // Derive output path.
    var as_of_buf: [10]u8 = undefined;
    const as_of_str = as_of.format(&as_of_buf);

    const derived_path = if (out_override) |p|
        try allocator.dupe(u8, p)
    else
        try deriveSnapshotPath(allocator, portfolio_path, as_of_str);
    defer allocator.free(derived_path);

    // Duplicate-skip check.
    if (!force and !dry_run) {
        if (std.fs.cwd().access(derived_path, .{})) |_| {
            var msg_buf: [256]u8 = undefined;
            const msg = std.fmt.bufPrint(&msg_buf, "snapshot for {s} already exists: {s} (use --force to overwrite)\n", .{ as_of_str, derived_path }) catch "snapshot already exists\n";
            try cli.stderrPrint(msg);
            return;
        } else |_| {}
    }

    // Build and render the snapshot.
    var snap = try buildSnapshot(allocator, &portfolio, portfolio_path, svc, prices, syms, as_of, qdates);
    defer snap.deinit(allocator);

    const rendered = try renderSnapshot(allocator, snap);
    defer allocator.free(rendered);

    if (dry_run) {
        try out.writeAll(rendered);
        return;
    }

    // Ensure history/ directory exists.
    if (std.fs.path.dirname(derived_path)) |dir| {
        std.fs.cwd().makePath(dir) catch |err| switch (err) {
            error.PathAlreadyExists => {},
            else => {
                try cli.stderrPrint("Error creating history directory: ");
                try cli.stderrPrint(@errorName(err));
                try cli.stderrPrint("\n");
                return err;
            },
        };
    }

    atomic.writeFileAtomic(allocator, derived_path, rendered) catch |err| {
        try cli.stderrPrint("Error writing snapshot: ");
        try cli.stderrPrint(@errorName(err));
        try cli.stderrPrint("\n");
        return err;
    };

    try out.print("snapshot written: {s}\n", .{derived_path});
}

// ── Path helpers ─────────────────────────────────────────────

/// Derive `<dir(portfolio_path)>/history/<as_of>-portfolio.srf`.
/// Caller owns returned memory.
pub fn deriveSnapshotPath(
    allocator: std.mem.Allocator,
    portfolio_path: []const u8,
    as_of_str: []const u8,
) ![]const u8 {
    const dir = std.fs.path.dirname(portfolio_path) orelse ".";
    const filename = try std.fmt.allocPrint(allocator, "{s}-portfolio.srf", .{as_of_str});
    defer allocator.free(filename);
    return std.fs.path.join(allocator, &.{ dir, "history", filename });
}

// ── Quote-date / as_of_date helpers ──────────────────────────

/// Per-symbol quote-date info gathered from the candle cache.
pub const QuoteInfo = struct {
    symbol: []const u8, // borrowed from caller
    /// Most recent candle date in cache, if any candles exist.
    last_date: ?Date,
    /// True when the symbol is classified money-market (excluded from
    /// as_of_date computation because MM candles are often stale but
    /// dollar-impact is nil).
    is_money_market: bool,
};

pub const QuoteDates = struct {
    /// Per-symbol info (same order as input `symbols`).
    dates: []QuoteInfo,
};

/// Gather quote-date info for each symbol from the cache. Does not
/// fetch; relies on whatever the cache has. Symbols with no candles at
/// all get `last_date = null`.
pub fn collectQuoteDates(
    allocator: std.mem.Allocator,
    svc: *zfin.DataService,
    symbols: []const []const u8,
) !QuoteDates {
    var list = try allocator.alloc(QuoteInfo, symbols.len);
    errdefer allocator.free(list);

    for (symbols, 0..) |sym, idx| {
        const is_mm = portfolio_mod.isMoneyMarketSymbol(sym);
        var last_date: ?Date = null;
        if (svc.getCachedCandles(sym)) |cs| {
            defer allocator.free(cs);
            if (cs.len > 0) last_date = cs[cs.len - 1].date;
        }
        list[idx] = .{ .symbol = sym, .last_date = last_date, .is_money_market = is_mm };
    }

    return .{ .dates = list };
}

/// Compute the snapshot's `as_of_date` from per-symbol quote info.
///
/// Rule: take the **mode** of `last_date` across non-MM symbols with a
/// known date; break ties by picking the maximum. If no non-MM symbol
/// has a date (portfolio is all cash/MM, or totally uncached), return
/// null and the caller falls back to the capture date.
pub fn computeAsOfDate(infos: []const QuoteInfo) ?Date {
    // Two-pass mode: count occurrences, then pick max-count/max-date.
    // With typical portfolios (~30 symbols) O(n²) is fine.
    var best: ?Date = null;
    var best_count: usize = 0;

    for (infos) |a| {
        if (a.is_money_market) continue;
        const a_date = a.last_date orelse continue;

        var count: usize = 0;
        for (infos) |b| {
            if (b.is_money_market) continue;
            const b_date = b.last_date orelse continue;
            if (a_date.eql(b_date)) count += 1;
        }

        if (count > best_count or
            (count == best_count and best != null and best.?.lessThan(a_date)))
        {
            best = a_date;
            best_count = count;
        }
    }

    return best;
}

/// Return (min, max) of non-MM symbol quote dates, for metadata.
/// Returns null if no non-MM symbol has a known date.
pub fn quoteDateRange(infos: []const QuoteInfo) ?struct { min: Date, max: Date } {
    var min_d: ?Date = null;
    var max_d: ?Date = null;
    for (infos) |info| {
        if (info.is_money_market) continue;
        const d = info.last_date orelse continue;
        if (min_d == null or d.lessThan(min_d.?)) min_d = d;
        if (max_d == null or max_d.?.lessThan(d)) max_d = d;
    }
    if (min_d == null) return null;
    return .{ .min = min_d.?, .max = max_d.? };
}

// ── Snapshot records ─────────────────────────────────────────
//
// Each record kind below is a plain struct suitable for `srf.fmtFrom`.
// Field order in the struct declaration IS the on-disk order — srf's
// `Record.from` iterates `inline for (info.fields)`. The leading `kind`
// field is the discriminator readers demux on.
//
// IMPORTANT: `kind` does NOT have a default value. SRF elides fields
// whose value matches the declared default (see setField in srf.zig),
// so a `kind: []const u8 = "meta"` would vanish from the output. Each
// construction site supplies the tag explicitly.
//
// Optional fields default to `null` so they're elided on null values —
// that's the behavior we want for `price`, `quote_date`, etc.

pub const MetaRow = struct {
    kind: []const u8,
    snapshot_version: u32,
    as_of_date: Date,
    captured_at: i64,
    zfin_version: []const u8,
    quote_date_min: ?Date = null,
    quote_date_max: ?Date = null,
    stale_count: usize,
};

pub const TotalRow = struct {
    kind: []const u8,
    scope: []const u8,
    value: f64,
};

pub const TaxTypeRow = struct {
    kind: []const u8,
    label: []const u8,
    value: f64,
};

pub const AccountRow = struct {
    kind: []const u8,
    name: []const u8,
    value: f64,
};

pub const LotRow = struct {
    kind: []const u8,
    symbol: []const u8,
    lot_symbol: []const u8,
    account: []const u8,
    security_type: []const u8,
    shares: f64,
    open_price: f64,
    cost_basis: f64,
    value: f64,
    /// Null for non-stock lots (cash/CD/illiquid have no per-share price).
    price: ?f64 = null,
    /// Null for non-stock lots.
    quote_date: ?Date = null,
    /// Emitted only when true (default is false, which srf skips).
    quote_stale: bool = false,
};

pub const Snapshot = struct {
    meta: MetaRow,
    totals: []TotalRow,
    tax_types: []TaxTypeRow,
    accounts: []AccountRow,
    lots: []LotRow,

    pub fn deinit(self: *Snapshot, allocator: std.mem.Allocator) void {
        allocator.free(self.totals);
        allocator.free(self.tax_types);
        allocator.free(self.accounts);
        allocator.free(self.lots);
    }
};

/// Build the full snapshot in memory. Does not touch disk.
fn buildSnapshot(
    allocator: std.mem.Allocator,
    portfolio: *zfin.Portfolio,
    portfolio_path: []const u8,
    svc: *zfin.DataService,
    prices: std.StringHashMap(f64),
    syms: []const []const u8,
    as_of: Date,
    qdates: QuoteDates,
) !Snapshot {
    // Totals
    const positions = try portfolio.positions(allocator);
    defer allocator.free(positions);

    var manual_set = try zfin.valuation.buildFallbackPrices(allocator, portfolio.lots, positions, @constCast(&prices));
    defer manual_set.deinit();

    var summary = try zfin.valuation.portfolioSummary(allocator, portfolio.*, positions, prices, manual_set);
    defer summary.deinit(allocator);

    const illiquid = portfolio.totalIlliquid();
    const net_worth = zfin.valuation.netWorth(portfolio.*, summary);

    var totals = try allocator.alloc(TotalRow, 3);
    totals[0] = .{ .kind = "total", .scope = "net_worth", .value = net_worth };
    totals[1] = .{ .kind = "total", .scope = "liquid", .value = summary.total_value };
    totals[2] = .{ .kind = "total", .scope = "illiquid", .value = illiquid };

    // Analysis (optional — depends on metadata.srf existing). If it
    // fails we still emit the snapshot with empty tax_type/account
    // sections rather than failing the whole capture.
    var tax_types: []TaxTypeRow = &.{};
    var accounts: []AccountRow = &.{};

    if (runAnalysis(allocator, portfolio, portfolio_path, svc, summary)) |result| {
        var a = result;
        defer a.deinit(allocator);

        tax_types = try allocator.alloc(TaxTypeRow, a.tax_type.len);
        for (a.tax_type, 0..) |t, idx| {
            tax_types[idx] = .{ .kind = "tax_type", .label = t.label, .value = t.value };
        }
        errdefer allocator.free(tax_types);

        accounts = try allocator.alloc(AccountRow, a.account.len);
        for (a.account, 0..) |acc, idx| {
            accounts[idx] = .{ .kind = "account", .name = acc.label, .value = acc.value };
        }
    } else |_| {
        // Silent: metadata.srf may legitimately not exist during initial
        // setup. Header is already emitted; missing-analysis just means
        // fewer breakdowns in the snapshot.
    }

    // Per-lot rows (open lots only). Stock lots get current price +
    // stale flag; non-stock lots get face value.
    var lots_list = std.ArrayList(LotRow).empty;
    errdefer lots_list.deinit(allocator);

    var stale_count: usize = 0;
    _ = syms;

    for (portfolio.lots) |lot| {
        if (!lot.isOpen()) continue;

        const sec_label = lot.security_type.label();
        const lot_sym = lot.symbol;
        const price_sym = lot.priceSymbol();
        const acct = lot.account orelse "";

        switch (lot.security_type) {
            .stock => {
                const raw_price = prices.get(price_sym) orelse lot.open_price;
                const is_manual = manual_set.contains(price_sym);
                const effective_price = if (is_manual) raw_price else raw_price * lot.price_ratio;
                const value = lot.shares * effective_price;

                var quote_date: ?Date = null;
                for (qdates.dates) |qi| {
                    if (std.mem.eql(u8, qi.symbol, price_sym)) {
                        quote_date = qi.last_date;
                        break;
                    }
                }
                const stale = if (quote_date) |qd| !qd.eql(as_of) else false;
                if (stale and !portfolio_mod.isMoneyMarketSymbol(price_sym)) stale_count += 1;

                try lots_list.append(allocator, .{
                    .kind = "lot",
                    .symbol = price_sym,
                    .lot_symbol = lot_sym,
                    .account = acct,
                    .security_type = sec_label,
                    .shares = lot.shares,
                    .open_price = lot.open_price,
                    .cost_basis = lot.costBasis(),
                    .price = effective_price,
                    .value = value,
                    .quote_date = quote_date,
                    .quote_stale = stale,
                });
            },
            .cash, .cd, .illiquid => {
                // `shares` is the face/dollar value for these types.
                try lots_list.append(allocator, .{
                    .kind = "lot",
                    .symbol = lot_sym,
                    .lot_symbol = lot_sym,
                    .account = acct,
                    .security_type = sec_label,
                    .shares = lot.shares,
                    .open_price = 0,
                    .cost_basis = 0,
                    .value = lot.shares,
                });
            },
            .option => {
                const opt_value = @abs(lot.shares) * lot.open_price * lot.multiplier;
                try lots_list.append(allocator, .{
                    .kind = "lot",
                    .symbol = lot_sym,
                    .lot_symbol = lot_sym,
                    .account = acct,
                    .security_type = sec_label,
                    .shares = lot.shares,
                    .open_price = lot.open_price,
                    .cost_basis = opt_value,
                    .value = opt_value,
                });
            },
            .watch => {
                // Watchlist lots aren't positions — skip.
            },
        }
    }

    const range = quoteDateRange(qdates.dates);

    return .{
        .meta = .{
            .kind = "meta",
            .snapshot_version = 1,
            .as_of_date = as_of,
            .captured_at = std.time.timestamp(),
            .zfin_version = version.version_string,
            .quote_date_min = if (range) |r| r.min else null,
            .quote_date_max = if (range) |r| r.max else null,
            .stale_count = stale_count,
        },
        .totals = totals,
        .tax_types = tax_types,
        .accounts = accounts,
        .lots = try lots_list.toOwnedSlice(allocator),
    };
}

fn runAnalysis(
    allocator: std.mem.Allocator,
    portfolio: *zfin.Portfolio,
    portfolio_path: []const u8,
    svc: *zfin.DataService,
    summary: zfin.valuation.PortfolioSummary,
) !zfin.analysis.AnalysisResult {
    const dir_end = if (std.mem.lastIndexOfScalar(u8, portfolio_path, std.fs.path.sep)) |idx| idx + 1 else 0;
    const meta_path = try std.fmt.allocPrint(allocator, "{s}metadata.srf", .{portfolio_path[0..dir_end]});
    defer allocator.free(meta_path);

    const meta_data = std.fs.cwd().readFileAlloc(allocator, meta_path, 1024 * 1024) catch return error.NoMetadata;
    defer allocator.free(meta_data);

    var cm = zfin.classification.parseClassificationFile(allocator, meta_data) catch return error.BadMetadata;
    defer cm.deinit();

    var acct_map_opt: ?zfin.analysis.AccountMap = svc.loadAccountMap(portfolio_path);
    defer if (acct_map_opt) |*am| am.deinit();

    return zfin.analysis.analyzePortfolio(
        allocator,
        summary.allocations,
        cm,
        portfolio.*,
        summary.total_value,
        acct_map_opt,
    );
}

// ── SRF rendering ────────────────────────────────────────────

/// Render a snapshot to SRF bytes. Caller owns result.
///
/// Each section is emitted as a homogeneous record slice via
/// `srf.fmtFrom`. The first section (meta) carries `emit_directives =
/// true` so the `#!srfv1` header and `#!created=...` line are written
/// once at the top; subsequent sections set `emit_directives = false`
/// to suppress a duplicate header.
pub fn renderSnapshot(allocator: std.mem.Allocator, snap: Snapshot) ![]const u8 {
    var aw: std.Io.Writer.Allocating = .init(allocator);
    errdefer aw.deinit();
    const w = &aw.writer;

    // Single-element slice so we can route the meta row through the
    // same `fmtFrom` pipeline as the rest of the sections. This also
    // puts the `#!created=...` header at the top of the file.
    const meta_rows: [1]MetaRow = .{snap.meta};
    try w.print("{f}", .{srf.fmtFrom(MetaRow, allocator, &meta_rows, .{
        .emit_directives = true,
        .created = snap.meta.captured_at,
    })});

    // Subsequent sections: records only (no header).
    const tail_opts: srf.FormatOptions = .{ .emit_directives = false };
    try w.print("{f}", .{srf.fmtFrom(TotalRow, allocator, snap.totals, tail_opts)});
    try w.print("{f}", .{srf.fmtFrom(TaxTypeRow, allocator, snap.tax_types, tail_opts)});
    try w.print("{f}", .{srf.fmtFrom(AccountRow, allocator, snap.accounts, tail_opts)});
    try w.print("{f}", .{srf.fmtFrom(LotRow, allocator, snap.lots, tail_opts)});

    return aw.toOwnedSlice();
}

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

const testing = std.testing;

test "deriveSnapshotPath: standard layout" {
    // Build the input portfolio path and expected output from
    // path-joined components so the test runs on both POSIX and Windows.
    const portfolio_path = try std.fs.path.join(
        testing.allocator,
        &.{ "home", "lobo", "finance", "portfolio.srf" },
    );
    defer testing.allocator.free(portfolio_path);

    const expected = try std.fs.path.join(
        testing.allocator,
        &.{ "home", "lobo", "finance", "history", "2026-04-20-portfolio.srf" },
    );
    defer testing.allocator.free(expected);

    const p = try deriveSnapshotPath(testing.allocator, portfolio_path, "2026-04-20");
    defer testing.allocator.free(p);
    try testing.expectEqualStrings(expected, p);
}

test "deriveSnapshotPath: bare filename (no dir) falls back to cwd" {
    const expected = try std.fs.path.join(
        testing.allocator,
        &.{ ".", "history", "2026-04-20-portfolio.srf" },
    );
    defer testing.allocator.free(expected);

    const p = try deriveSnapshotPath(testing.allocator, "portfolio.srf", "2026-04-20");
    defer testing.allocator.free(p);
    try testing.expectEqualStrings(expected, p);
}

test "computeAsOfDate: mode of non-MM dates, ties broken by max" {
    const d1 = Date.fromYmd(2026, 4, 17);
    const d2 = Date.fromYmd(2026, 4, 20);
    const infos = [_]QuoteInfo{
        .{ .symbol = "VTI", .last_date = d2, .is_money_market = false },
        .{ .symbol = "AAPL", .last_date = d2, .is_money_market = false },
        .{ .symbol = "MSFT", .last_date = d1, .is_money_market = false },
        // Money-market with stale date — must not win the mode.
        .{ .symbol = "SWVXX", .last_date = Date.fromYmd(2025, 1, 1), .is_money_market = true },
    };
    const result = computeAsOfDate(&infos);
    try testing.expect(result != null);
    try testing.expect(result.?.eql(d2));
}

test "computeAsOfDate: ties break toward max date" {
    const d1 = Date.fromYmd(2026, 4, 17);
    const d2 = Date.fromYmd(2026, 4, 20);
    const infos = [_]QuoteInfo{
        .{ .symbol = "A", .last_date = d1, .is_money_market = false },
        .{ .symbol = "B", .last_date = d2, .is_money_market = false },
    };
    const result = computeAsOfDate(&infos).?;
    try testing.expect(result.eql(d2));
}

test "computeAsOfDate: all MM returns null" {
    const infos = [_]QuoteInfo{
        .{ .symbol = "SWVXX", .last_date = Date.fromYmd(2026, 4, 20), .is_money_market = true },
        .{ .symbol = "VMFXX", .last_date = Date.fromYmd(2026, 4, 20), .is_money_market = true },
    };
    try testing.expect(computeAsOfDate(&infos) == null);
}

test "computeAsOfDate: symbols with no cached date are ignored" {
    const d = Date.fromYmd(2026, 4, 20);
    const infos = [_]QuoteInfo{
        .{ .symbol = "VTI", .last_date = d, .is_money_market = false },
        .{ .symbol = "UNCACHED", .last_date = null, .is_money_market = false },
    };
    const result = computeAsOfDate(&infos).?;
    try testing.expect(result.eql(d));
}

test "computeAsOfDate: empty input returns null" {
    try testing.expect(computeAsOfDate(&.{}) == null);
}

test "quoteDateRange: min and max skip MM symbols" {
    const d_old = Date.fromYmd(2026, 4, 17);
    const d_new = Date.fromYmd(2026, 4, 20);
    const d_ancient = Date.fromYmd(2025, 1, 1);
    const infos = [_]QuoteInfo{
        .{ .symbol = "A", .last_date = d_new, .is_money_market = false },
        .{ .symbol = "B", .last_date = d_old, .is_money_market = false },
        // MM way older — must be excluded from the range.
        .{ .symbol = "SWVXX", .last_date = d_ancient, .is_money_market = true },
    };
    const r = quoteDateRange(&infos).?;
    try testing.expect(r.min.eql(d_old));
    try testing.expect(r.max.eql(d_new));
}

test "quoteDateRange: returns null when no non-MM data" {
    const infos = [_]QuoteInfo{
        .{ .symbol = "SWVXX", .last_date = Date.fromYmd(2026, 4, 20), .is_money_market = true },
    };
    try testing.expect(quoteDateRange(&infos) == null);
}

test "renderSnapshot: minimal snapshot shape" {
    const totals = [_]TotalRow{
        .{ .kind = "total", .scope = "net_worth", .value = 1000.0 },
        .{ .kind = "total", .scope = "liquid", .value = 800.0 },
        .{ .kind = "total", .scope = "illiquid", .value = 200.0 },
    };
    const snap: Snapshot = .{
        .meta = .{
            .kind = "meta",
            .snapshot_version = 1,
            .as_of_date = Date.fromYmd(2026, 4, 20),
            .captured_at = 1_745_222_400,
            .zfin_version = "testver",
            .stale_count = 0,
        },
        .totals = @constCast(&totals),
        .tax_types = &.{},
        .accounts = &.{},
        .lots = &.{},
    };

    const rendered = try renderSnapshot(testing.allocator, snap);
    defer testing.allocator.free(rendered);

    // Header + front-matter from the first fmtFrom call.
    try testing.expect(std.mem.startsWith(u8, rendered, "#!srfv1\n"));
    try testing.expect(std.mem.indexOf(u8, rendered, "#!created=1745222400") != null);

    // Meta record fields (discriminator, version, date, captured_at).
    try testing.expect(std.mem.indexOf(u8, rendered, "kind::meta") != null);
    try testing.expect(std.mem.indexOf(u8, rendered, "as_of_date::2026-04-20") != null);
    try testing.expect(std.mem.indexOf(u8, rendered, "zfin_version::testver") != null);

    // Totals records use kind::total plus scope+value.
    try testing.expect(std.mem.indexOf(u8, rendered, "kind::total,scope::net_worth") != null);
    try testing.expect(std.mem.indexOf(u8, rendered, "kind::total,scope::liquid") != null);
    try testing.expect(std.mem.indexOf(u8, rendered, "kind::total,scope::illiquid") != null);
}

test "renderSnapshot: includes quote_date_min/max when present, elided when null" {
    const snap_with: Snapshot = .{
        .meta = .{
            .kind = "meta",
            .snapshot_version = 1,
            .as_of_date = Date.fromYmd(2026, 4, 20),
            .captured_at = 0,
            .zfin_version = "x",
            .quote_date_min = Date.fromYmd(2026, 4, 17),
            .quote_date_max = Date.fromYmd(2026, 4, 20),
            .stale_count = 2,
        },
        .totals = &.{},
        .tax_types = &.{},
        .accounts = &.{},
        .lots = &.{},
    };
    const rendered_with = try renderSnapshot(testing.allocator, snap_with);
    defer testing.allocator.free(rendered_with);
    try testing.expect(std.mem.indexOf(u8, rendered_with, "quote_date_min::2026-04-17") != null);
    try testing.expect(std.mem.indexOf(u8, rendered_with, "quote_date_max::2026-04-20") != null);
    try testing.expect(std.mem.indexOf(u8, rendered_with, "stale_count:num:2") != null);

    // Same structure with nulls — srf elides optional fields matching
    // their `null` default, so those keys must NOT appear.
    const snap_without: Snapshot = .{
        .meta = .{
            .kind = "meta",
            .snapshot_version = 1,
            .as_of_date = Date.fromYmd(2026, 4, 20),
            .captured_at = 0,
            .zfin_version = "x",
            .stale_count = 0,
        },
        .totals = &.{},
        .tax_types = &.{},
        .accounts = &.{},
        .lots = &.{},
    };
    const rendered_without = try renderSnapshot(testing.allocator, snap_without);
    defer testing.allocator.free(rendered_without);
    try testing.expect(std.mem.indexOf(u8, rendered_without, "quote_date_min") == null);
    try testing.expect(std.mem.indexOf(u8, rendered_without, "quote_date_max") == null);
}

test "renderSnapshot: lot rendering elides price/quote_date/stale when default" {
    const lots = [_]LotRow{
        // Stock lot — all three optional fields populated.
        .{
            .kind = "lot",
            .symbol = "VTI",
            .lot_symbol = "VTI",
            .account = "Emil Roth",
            .security_type = "Stock",
            .shares = 100,
            .open_price = 200.0,
            .cost_basis = 20000.0,
            .value = 31002.0,
            .price = 310.02,
            .quote_date = Date.fromYmd(2026, 4, 17),
            .quote_stale = true,
        },
        // Cash lot — optionals left at default (null / false), so srf
        // elides them.
        .{
            .kind = "lot",
            .symbol = "Savings",
            .lot_symbol = "Savings",
            .account = "Emil Roth",
            .security_type = "Cash",
            .shares = 50000,
            .open_price = 0,
            .cost_basis = 0,
            .value = 50000,
        },
    };
    const snap: Snapshot = .{
        .meta = .{
            .kind = "meta",
            .snapshot_version = 1,
            .as_of_date = Date.fromYmd(2026, 4, 20),
            .captured_at = 0,
            .zfin_version = "x",
            .stale_count = 1,
        },
        .totals = &.{},
        .tax_types = &.{},
        .accounts = &.{},
        .lots = @constCast(&lots),
    };
    const rendered = try renderSnapshot(testing.allocator, snap);
    defer testing.allocator.free(rendered);

    // Stock lot line: extract it so we can check in isolation.
    const vti_start = std.mem.indexOf(u8, rendered, "kind::lot,symbol::VTI").?;
    const vti_end = std.mem.indexOfScalarPos(u8, rendered, vti_start, '\n').?;
    const vti_line = rendered[vti_start..vti_end];
    // All three optional-on-stock fields present.
    try testing.expect(std.mem.indexOf(u8, vti_line, ",price:num:") != null);
    try testing.expect(std.mem.indexOf(u8, vti_line, "quote_date::2026-04-17") != null);
    try testing.expect(std.mem.indexOf(u8, vti_line, "quote_stale") != null);

    // Cash lot line: the three optional fields must be elided because
    // they match their declared defaults (null, null, false).
    const cash_start = std.mem.indexOf(u8, rendered, "kind::lot,symbol::Savings").?;
    const cash_end = std.mem.indexOfScalarPos(u8, rendered, cash_start, '\n').?;
    const cash_line = rendered[cash_start..cash_end];
    try testing.expect(std.mem.indexOf(u8, cash_line, ",price:num:") == null);
    try testing.expect(std.mem.indexOf(u8, cash_line, "quote_date") == null);
    try testing.expect(std.mem.indexOf(u8, cash_line, "quote_stale") == null);
}

test "renderSnapshot: tax_type and account rows carry kind discriminator" {
    const tax = [_]TaxTypeRow{
        .{ .kind = "tax_type", .label = "Taxable", .value = 5000 },
        .{ .kind = "tax_type", .label = "Roth (Post-Tax)", .value = 3000 },
    };
    const accts = [_]AccountRow{
        .{ .kind = "account", .name = "Emil Roth", .value = 2500 },
    };
    const snap: Snapshot = .{
        .meta = .{
            .kind = "meta",
            .snapshot_version = 1,
            .as_of_date = Date.fromYmd(2026, 4, 20),
            .captured_at = 0,
            .zfin_version = "x",
            .stale_count = 0,
        },
        .totals = &.{},
        .tax_types = @constCast(&tax),
        .accounts = @constCast(&accts),
        .lots = &.{},
    };
    const rendered = try renderSnapshot(testing.allocator, snap);
    defer testing.allocator.free(rendered);
    try testing.expect(std.mem.indexOf(u8, rendered, "kind::tax_type,label::Taxable") != null);
    try testing.expect(std.mem.indexOf(u8, rendered, "kind::tax_type,label::Roth (Post-Tax)") != null);
    try testing.expect(std.mem.indexOf(u8, rendered, "kind::account,name::Emil Roth") != null);
}

test "renderSnapshot: front-matter emitted exactly once" {
    // All four tail sections use emit_directives=false; only the meta
    // call produces the #!srfv1 + #!created lines. Make sure we don't
    // regress into duplicate headers.
    const totals = [_]TotalRow{
        .{ .kind = "total", .scope = "net_worth", .value = 1000 },
    };
    const snap: Snapshot = .{
        .meta = .{
            .kind = "meta",
            .snapshot_version = 1,
            .as_of_date = Date.fromYmd(2026, 4, 20),
            .captured_at = 1,
            .zfin_version = "x",
            .stale_count = 0,
        },
        .totals = @constCast(&totals),
        .tax_types = &.{},
        .accounts = &.{},
        .lots = &.{},
    };
    const rendered = try renderSnapshot(testing.allocator, snap);
    defer testing.allocator.free(rendered);
    try testing.expectEqual(@as(usize, 1), std.mem.count(u8, rendered, "#!srfv1"));
    try testing.expectEqual(@as(usize, 1), std.mem.count(u8, rendered, "#!created="));
}