/// Portfolio analysis engine.
///
/// Takes portfolio allocations (with market values) and classification metadata,
/// produces breakdowns by asset class, sector, geographic region, account, and tax type.
const std = @import("std");
const srf = @import("srf");
const Allocation = @import("valuation.zig").Allocation;
const ClassificationEntry = @import("../models/classification.zig").ClassificationEntry;
const ClassificationMap = @import("../models/classification.zig").ClassificationMap;
const LotType = @import("../models/portfolio.zig").LotType;
const Portfolio = @import("../models/portfolio.zig").Portfolio;
const Date = @import("../models/date.zig").Date;

/// A single slice of a breakdown (e.g., "Technology" -> 25.3%)
pub const BreakdownItem = struct {
    label: []const u8,
    value: f64, // dollar amount
    weight: f64, // fraction of total (0.0 - 1.0)
};

/// Tax type classification for accounts.
pub const TaxType = enum {
    taxable,
    roth,
    traditional,
    hsa,

    pub fn label(self: TaxType) []const u8 {
        return switch (self) {
            .taxable => "Taxable",
            .roth => "Roth (Post-Tax)",
            .traditional => "Traditional (Pre-Tax)",
            .hsa => "HSA (Triple Tax-Free)",
        };
    }
};

/// Account tax type classification entry, parsed from accounts.srf.
pub const AccountTaxEntry = struct {
    account: []const u8,
    tax_type: TaxType,
    institution: ?[]const u8 = null,
    account_number: ?[]const u8 = null,
    update_cadence: UpdateCadence = .weekly,
    /// When true, raw cash-balance changes (`cash_delta` in the
    /// contributions diff) on this account roll up into the
    /// attribution total as real contributions.
    ///
    /// Defaults to false because most cash accounts generate
    /// `cash_delta` entries from internal movement — interest posting,
    /// dividend credit, CD coupon, settlement sweeps — that would
    /// inflate the attribution number if counted. Set to true only
    /// for accounts whose cash movement is dominated by external
    /// contributions (payroll ESPP accrual, direct 401k cash
    /// deposits). See TODO.md for the design history.
    cash_is_contribution: bool = false,
    /// When true, marks the account as a direct-indexing proxy
    /// (lots track a benchmark with tracking-error drift rather
    /// than holding the benchmark directly). Two behaviors:
    ///
    ///   1. Contributions (`zfin contributions` / `zfin compare`
    ///      attribution): the edit-detection residual tolerance is
    ///      loosened from 0.01% (noise floor) to 1% — tracking-
    ///      error share reconciliation no longer lands in
    ///      `rollup_delta` / `drip_negative` and the attribution
    ///      total stays clean.
    ///
    ///   2. Audit (`zfin audit` ratio-suggestions section): lots
    ///      with `price_ratio == 1.0` in this account get a
    ///      suggested ratio to bridge the brokerage vs. portfolio
    ///      value gap. Default audit behavior skips ratio == 1.0
    ///      lots since there's nothing to adjust; direct-indexing
    ///      accounts opt out of that skip.
    ///
    /// Not a general "ignore drift" flag — use only for accounts
    /// whose underlying lots explicitly track a benchmark (e.g. a
    /// basket of 500 individual stocks tracked as SPY via `ticker::`
    /// alias).
    direct_indexing: bool = false,
};

/// Update cadence for manual account maintenance. Parsed from accounts.srf.
/// Default is `weekly` (fail-open: every account nags until explicitly silenced).
pub const UpdateCadence = enum {
    weekly,
    monthly,
    quarterly,
    none,

    /// Number of calendar days before an account is considered overdue.
    pub fn thresholdDays(self: UpdateCadence) ?u32 {
        return switch (self) {
            .weekly => 7,
            .monthly => 30,
            .quarterly => 90,
            .none => null,
        };
    }

    pub fn label(self: UpdateCadence) []const u8 {
        return switch (self) {
            .weekly => "weekly",
            .monthly => "monthly",
            .quarterly => "quarterly",
            .none => "none",
        };
    }
};

/// Parsed account metadata.
pub const AccountMap = struct {
    entries: []AccountTaxEntry,
    allocator: std.mem.Allocator,

    pub fn deinit(self: *AccountMap) void {
        for (self.entries) |e| {
            self.allocator.free(e.account);
            if (e.institution) |s| self.allocator.free(s);
            if (e.account_number) |s| self.allocator.free(s);
        }
        self.allocator.free(self.entries);
    }

    /// Look up the tax type label for a given account name.
    pub fn taxTypeFor(self: AccountMap, account: []const u8) []const u8 {
        for (self.entries) |e| {
            if (std.mem.eql(u8, e.account, account)) {
                return e.tax_type.label();
            }
        }
        return "Unknown";
    }

    /// Find the portfolio account name for a given institution + account number.
    pub fn findByInstitutionAccount(self: AccountMap, institution: []const u8, account_number: []const u8) ?[]const u8 {
        for (self.entries) |e| {
            if (e.institution) |inst| {
                if (e.account_number) |num| {
                    if (std.mem.eql(u8, inst, institution) and std.mem.eql(u8, num, account_number))
                        return e.account;
                }
            }
        }
        return null;
    }

    /// Return all entries matching a given institution.
    pub fn entriesForInstitution(self: AccountMap, institution: []const u8) []const AccountTaxEntry {
        var count: usize = 0;
        for (self.entries) |e| {
            if (e.institution) |inst| {
                if (std.mem.eql(u8, inst, institution)) count += 1;
            }
        }
        if (count == 0) return &.{};
        return self.entries;
    }

    /// Is cash-balance movement on `account` treated as a real
    /// contribution (vs. internal noise) for the attribution total?
    /// Defaults to false when the account isn't in the map.
    pub fn cashIsContribution(self: AccountMap, account: []const u8) bool {
        for (self.entries) |e| {
            if (std.mem.eql(u8, e.account, account)) {
                return e.cash_is_contribution;
            }
        }
        return false;
    }

    /// Is `account` flagged as a direct-indexing proxy? See
    /// `AccountTaxEntry.direct_indexing` for the two behaviors this
    /// drives. Defaults to false when the account isn't in the map.
    pub fn isDirectIndexing(self: AccountMap, account: []const u8) bool {
        for (self.entries) |e| {
            if (std.mem.eql(u8, e.account, account)) {
                return e.direct_indexing;
            }
        }
        return false;
    }
};

/// Parse an accounts.srf file into an AccountMap.
/// Each record has: account::<NAME>,tax_type::<TYPE>[,institution::<INST>][,account_number::<NUM>]
pub fn parseAccountsFile(allocator: std.mem.Allocator, data: []const u8) !AccountMap {
    var entries = std.ArrayList(AccountTaxEntry).empty;
    errdefer {
        for (entries.items) |e| {
            allocator.free(e.account);
            if (e.institution) |s| allocator.free(s);
            if (e.account_number) |s| allocator.free(s);
        }
        entries.deinit(allocator);
    }

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

    while (try it.next()) |fields| {
        const entry = fields.to(AccountTaxEntry) catch continue;
        try entries.append(allocator, .{
            .account = try allocator.dupe(u8, entry.account),
            .tax_type = entry.tax_type,
            .institution = if (entry.institution) |s| try allocator.dupe(u8, s) else null,
            .account_number = if (entry.account_number) |s| try allocator.dupe(u8, s) else null,
            .update_cadence = entry.update_cadence,
            .cash_is_contribution = entry.cash_is_contribution,
            .direct_indexing = entry.direct_indexing,
        });
    }

    return .{
        .entries = try entries.toOwnedSlice(allocator),
        .allocator = allocator,
    };
}

/// Complete portfolio analysis result.
pub const AnalysisResult = struct {
    /// Breakdown by asset class (US Large Cap, Bonds, Cash & CDs, etc.)
    asset_class: []BreakdownItem,
    /// Breakdown by sector (Technology, Healthcare, etc.) -- equities only
    sector: []BreakdownItem,
    /// Breakdown by geographic region (US, International, etc.)
    geo: []BreakdownItem,
    /// Breakdown by account name
    account: []BreakdownItem,
    /// Breakdown by tax type (Taxable, Roth, Traditional, HSA)
    tax_type: []BreakdownItem,
    /// Positions not covered by classification metadata
    unclassified: []const []const u8,
    /// Total portfolio value used as denominator
    total_value: f64,

    pub fn deinit(self: *AnalysisResult, allocator: std.mem.Allocator) void {
        allocator.free(self.asset_class);
        allocator.free(self.sector);
        allocator.free(self.geo);
        allocator.free(self.account);
        allocator.free(self.tax_type);
        allocator.free(self.unclassified);
    }
};

/// Compute portfolio analysis from allocations and classification metadata.
/// `allocations` are the stock/ETF positions with market values.
/// `classifications` is the metadata file data.
/// `portfolio` is the full portfolio (for cash/CD/illiquid totals).
/// `account_map` is optional account tax type metadata.
/// `as_of` is the date against which lot open/closed status is
/// evaluated. Pass `null` to use wall-clock today (the default for
/// interactive commands); historical snapshot backfill passes the
/// target date so lots opened/closed/matured between `as_of` and today
/// are counted correctly.
pub fn analyzePortfolio(
    allocator: std.mem.Allocator,
    allocations: []const Allocation,
    classifications: ClassificationMap,
    portfolio: Portfolio,
    total_portfolio_value: f64,
    account_map: ?AccountMap,
    as_of: ?Date,
) !AnalysisResult {
    // Accumulators: label -> dollar amount
    var ac_map = std.StringHashMap(f64).init(allocator);
    defer ac_map.deinit();
    var sector_map = std.StringHashMap(f64).init(allocator);
    defer sector_map.deinit();
    var geo_map = std.StringHashMap(f64).init(allocator);
    defer geo_map.deinit();
    var acct_map = std.StringHashMap(f64).init(allocator);
    defer acct_map.deinit();
    var tax_map = std.StringHashMap(f64).init(allocator);
    defer tax_map.deinit();

    var unclassified_list = std.ArrayList([]const u8).empty;
    errdefer unclassified_list.deinit(allocator);

    // Process each equity allocation (for asset class, sector, geo, unclassified)
    for (allocations) |alloc| {
        const mv = alloc.market_value;
        if (mv <= 0) continue;

        // Find classification entries for this symbol
        // Try both the raw symbol and display_symbol
        var found = false;
        for (classifications.entries) |entry| {
            if (std.mem.eql(u8, entry.symbol, alloc.symbol) or
                std.mem.eql(u8, entry.symbol, alloc.display_symbol))
            {
                found = true;
                const frac = entry.pct / 100.0;
                const portion = mv * frac;

                if (entry.asset_class) |ac| {
                    const prev = ac_map.get(ac) orelse 0;
                    ac_map.put(ac, prev + portion) catch {};
                }
                if (entry.sector) |s| {
                    const prev = sector_map.get(s) orelse 0;
                    sector_map.put(s, prev + portion) catch {};
                }
                if (entry.geo) |g| {
                    const prev = geo_map.get(g) orelse 0;
                    geo_map.put(g, prev + portion) catch {};
                }
            }
        }
        if (!found) {
            try unclassified_list.append(allocator, alloc.display_symbol);
        }
    }

    // Build symbol -> (current_price, price_ratio) lookup from allocations.
    // For unmerged allocations, current_price already includes price_ratio (preadjusted).
    // For merged allocations, current_price is the base-ticker price (not preadjusted).
    const PriceEntry = struct { price: f64, is_preadjusted: bool };
    var price_lookup = std.StringHashMap(PriceEntry).init(allocator);
    defer price_lookup.deinit();
    for (allocations) |alloc| {
        price_lookup.put(alloc.symbol, .{
            .price = alloc.current_price,
            .is_preadjusted = alloc.price_ratio != 1.0,
        }) catch {};
    }

    // Account breakdown from individual lots (avoids "Multiple" aggregation issue).
    // Use `lotIsOpenAsOf(as_of)` when provided so backfilled snapshots
    // correctly include/exclude lots based on the target date rather
    // than wall-clock today. `isOpen()` = `lotIsOpenAsOf(today)`.
    const reference_date = as_of orelse Date.fromEpoch(std.time.timestamp());
    for (portfolio.lots) |lot| {
        if (!lot.lotIsOpenAsOf(reference_date)) continue;
        const acct = lot.account orelse continue;
        const value: f64 = switch (lot.security_type) {
            .stock => blk: {
                if (price_lookup.get(lot.priceSymbol())) |entry| {
                    break :blk lot.marketValue(entry.price, entry.is_preadjusted);
                } else {
                    // Fallback to open_price (already in lot-specific terms)
                    break :blk lot.shares * lot.open_price;
                }
            },
            .cash => lot.shares,
            .cd => lot.shares, // face value
            .option => @abs(lot.shares) * lot.open_price,
            .illiquid, .watch => continue,
        };
        const prev = acct_map.get(acct) orelse 0;
        acct_map.put(acct, prev + value) catch {};
    }

    // Add non-stock asset classes (combine Cash + CDs)
    const cash_total = portfolio.totalCash();
    const cd_total = portfolio.totalCdFaceValue();
    const cash_cd_total = cash_total + cd_total;
    if (cash_cd_total > 0) {
        const prev = ac_map.get("Cash & CDs") orelse 0;
        ac_map.put("Cash & CDs", prev + cash_cd_total) catch {};
        const gprev = geo_map.get("US") orelse 0;
        geo_map.put("US", gprev + cash_cd_total) catch {};
    }
    const opt_total = portfolio.totalOptionCost();
    if (opt_total > 0) {
        const prev = ac_map.get("Options") orelse 0;
        ac_map.put("Options", prev + opt_total) catch {};
    }

    // Tax type breakdown: map each account's total to its tax type
    if (account_map) |am| {
        var acct_iter = acct_map.iterator();
        while (acct_iter.next()) |kv| {
            const tt = am.taxTypeFor(kv.key_ptr.*);
            const prev = tax_map.get(tt) orelse 0;
            tax_map.put(tt, prev + kv.value_ptr.*) catch {};
        }
    }

    // Convert maps to sorted slices
    const total = if (total_portfolio_value > 0) total_portfolio_value else 1.0;

    return .{
        .asset_class = try mapToSortedBreakdown(allocator, ac_map, total),
        .sector = try mapToSortedBreakdown(allocator, sector_map, total),
        .geo = try mapToSortedBreakdown(allocator, geo_map, total),
        .account = try mapToSortedBreakdown(allocator, acct_map, total),
        .tax_type = try mapToSortedBreakdown(allocator, tax_map, total),
        .unclassified = try unclassified_list.toOwnedSlice(allocator),
        .total_value = total_portfolio_value,
    };
}

/// Convert a label->value HashMap to a sorted BreakdownItem slice (descending by value).
fn mapToSortedBreakdown(
    allocator: std.mem.Allocator,
    map: std.StringHashMap(f64),
    total: f64,
) ![]BreakdownItem {
    var items = std.ArrayList(BreakdownItem).empty;
    errdefer items.deinit(allocator);

    var iter = map.iterator();
    while (iter.next()) |kv| {
        try items.append(allocator, .{
            .label = kv.key_ptr.*,
            .value = kv.value_ptr.*,
            .weight = kv.value_ptr.* / total,
        });
    }

    // Sort descending by value
    std.mem.sort(BreakdownItem, items.items, {}, struct {
        fn f(_: void, a: BreakdownItem, b: BreakdownItem) bool {
            return a.value > b.value;
        }
    }.f);

    return items.toOwnedSlice(allocator);
}

test "parseAccountsFile" {
    const data =
        \\#!srfv1
        \\account::Emil Roth,tax_type::roth
        \\account::Joint trust,tax_type::taxable
        \\account::Fidelity Emil HSA,tax_type::hsa
    ;
    const allocator = std.testing.allocator;
    var am = try parseAccountsFile(allocator, data);
    defer am.deinit();

    try std.testing.expectEqual(@as(usize, 3), am.entries.len);
    try std.testing.expectEqualStrings("Roth (Post-Tax)", am.taxTypeFor("Emil Roth"));
    try std.testing.expectEqualStrings("Taxable", am.taxTypeFor("Joint trust"));
    try std.testing.expectEqualStrings("HSA (Triple Tax-Free)", am.taxTypeFor("Fidelity Emil HSA"));
    try std.testing.expectEqualStrings("Unknown", am.taxTypeFor("Nonexistent"));
}

test "parseAccountsFile: cash_is_contribution default false, opt-in true" {
    const data =
        \\#!srfv1
        \\account::Kelly ESPP,tax_type::taxable,cash_is_contribution:bool:true
        \\account::Joint cash,tax_type::taxable
    ;
    const allocator = std.testing.allocator;
    var am = try parseAccountsFile(allocator, data);
    defer am.deinit();

    try std.testing.expectEqual(@as(usize, 2), am.entries.len);
    // Opted-in account
    try std.testing.expect(am.cashIsContribution("Kelly ESPP"));
    // Default-off account
    try std.testing.expect(!am.cashIsContribution("Joint cash"));
    // Unknown account defaults to false
    try std.testing.expect(!am.cashIsContribution("Nonexistent"));
}

test "parseAccountsFile: direct_indexing default false, opt-in true" {
    const data =
        \\#!srfv1
        \\account::Tax Loss,tax_type::taxable,direct_indexing:bool:true
        \\account::Regular Brokerage,tax_type::taxable
    ;
    const allocator = std.testing.allocator;
    var am = try parseAccountsFile(allocator, data);
    defer am.deinit();

    try std.testing.expectEqual(@as(usize, 2), am.entries.len);
    try std.testing.expect(am.isDirectIndexing("Tax Loss"));
    try std.testing.expect(!am.isDirectIndexing("Regular Brokerage"));
    try std.testing.expect(!am.isDirectIndexing("Nonexistent"));
}

test "TaxType.label" {
    try std.testing.expectEqualStrings("Taxable", TaxType.taxable.label());
    try std.testing.expectEqualStrings("Roth (Post-Tax)", TaxType.roth.label());
    try std.testing.expectEqualStrings("Traditional (Pre-Tax)", TaxType.traditional.label());
    try std.testing.expectEqualStrings("HSA (Triple Tax-Free)", TaxType.hsa.label());
}

test "mapToSortedBreakdown" {
    const allocator = std.testing.allocator;
    var map = std.StringHashMap(f64).init(allocator);
    defer map.deinit();
    try map.put("Technology", 50_000);
    try map.put("Healthcare", 30_000);
    try map.put("Energy", 20_000);

    const total = 100_000.0;
    const breakdown = try mapToSortedBreakdown(allocator, map, total);
    defer allocator.free(breakdown);

    try std.testing.expectEqual(@as(usize, 3), breakdown.len);
    // Should be sorted descending by value
    try std.testing.expectEqualStrings("Technology", breakdown[0].label);
    try std.testing.expectApproxEqAbs(@as(f64, 50_000), breakdown[0].value, 0.01);
    try std.testing.expectApproxEqAbs(@as(f64, 0.5), breakdown[0].weight, 0.001);
    try std.testing.expectEqualStrings("Healthcare", breakdown[1].label);
    try std.testing.expectEqualStrings("Energy", breakdown[2].label);
}

test "mapToSortedBreakdown empty" {
    const allocator = std.testing.allocator;
    var map = std.StringHashMap(f64).init(allocator);
    defer map.deinit();
    const breakdown = try mapToSortedBreakdown(allocator, map, 100_000.0);
    defer allocator.free(breakdown);
    try std.testing.expectEqual(@as(usize, 0), breakdown.len);
}

test "parseAccountsFile empty" {
    const allocator = std.testing.allocator;
    var am = try parseAccountsFile(allocator, "#!srfv1\n");
    defer am.deinit();
    try std.testing.expectEqual(@as(usize, 0), am.entries.len);
}

test "parseAccountsFile missing fields" {
    // Line with only account but no tax_type -> skipped via Record.to() error.
    // Override log level to suppress expected srf log.err output that
    // would otherwise cause the test runner to report failure.
    const prev_level = std.testing.log_level;
    std.testing.log_level = .err;
    defer std.testing.log_level = prev_level;
    const allocator = std.testing.allocator;
    var am = try parseAccountsFile(allocator, "#!srfv1\naccount::Test Account\n# comment\n");
    defer am.deinit();
    try std.testing.expectEqual(@as(usize, 0), am.entries.len);
}

test "account breakdown applies price_ratio" {
    const allocator = std.testing.allocator;
    const Lot = @import("../models/portfolio.zig").Lot;

    // Three lots across two accounts:
    // - Brokerage: direct SPY (ratio 1.0)
    // - 401(k): CIT mapped to SPY (ratio 0.25, merged allocation)
    // - 401(k): CUSIP with ticker=VTTHX (ratio 5.0, unmerged allocation)
    var lots = [_]Lot{
        .{
            .symbol = "SPY",
            .shares = 100,
            .open_date = Date.fromYmd(2020, 1, 1),
            .open_price = 400,
            .account = "Brokerage",
        },
        .{
            .symbol = "CIT-SPY",
            .shares = 500,
            .open_date = Date.fromYmd(2020, 1, 1),
            .open_price = 100,
            .ticker = "SPY",
            .price_ratio = 0.25,
            .account = "401(k)",
        },
        .{
            .symbol = "CUSIP123",
            .shares = 200,
            .open_date = Date.fromYmd(2020, 1, 1),
            .open_price = 50,
            .ticker = "VTTHX",
            .price_ratio = 5.0,
            .account = "401(k)",
        },
    };
    const portfolio = Portfolio{ .lots = &lots, .allocator = allocator };

    // Allocations as produced by portfolioSummary + mergeAllocsBySymbol:
    // SPY: merged (direct + CIT). current_price = base SPY price = 500, price_ratio = 1.0
    // VTTHX: unmerged. current_price = 30 * 5.0 = 150 (already includes ratio), price_ratio = 5.0
    const allocations = [_]Allocation{
        .{
            .symbol = "SPY",
            .display_symbol = "SPY",
            .shares = 225, // 100 + 500*0.25
            .avg_cost = 300,
            .current_price = 500, // base-ticker price (merged, ratio=1.0)
            .market_value = 112_500,
            .cost_basis = 67_500,
            .weight = 0.789,
            .unrealized_gain_loss = 45_000,
            .unrealized_return = 0.667,
            .price_ratio = 1.0, // merged
        },
        .{
            .symbol = "VTTHX",
            .display_symbol = "VTTHX",
            .shares = 200,
            .avg_cost = 50,
            .current_price = 150, // already includes price_ratio (30 * 5.0)
            .market_value = 30_000, // 200 * 150
            .cost_basis = 10_000,
            .weight = 0.211,
            .unrealized_gain_loss = 20_000,
            .unrealized_return = 2.0,
            .price_ratio = 5.0, // unmerged, ratio preserved
        },
    };

    const cm = ClassificationMap{ .entries = &.{}, .allocator = allocator };

    var result = try analyzePortfolio(
        allocator,
        &allocations,
        cm,
        portfolio,
        142_500,
        null,
        null,
    );
    defer result.deinit(allocator);

    // Expected account values:
    // Brokerage: SPY direct, 100 shares * $500 * 1.0 = $50,000
    // 401(k): CIT-SPY 500 shares * $500 * 0.25 = $62,500
    //       + CUSIP123 200 shares * $150 (already includes ratio) = $30,000
    //       = $92,500
    // Total: $142,500
    for (result.account) |item| {
        if (std.mem.eql(u8, item.label, "Brokerage")) {
            try std.testing.expectApproxEqAbs(@as(f64, 50_000), item.value, 1.0);
        } else if (std.mem.eql(u8, item.label, "401(k)")) {
            try std.testing.expectApproxEqAbs(@as(f64, 92_500), item.value, 1.0);
        }
    }

    // Sum of accounts must equal total portfolio value
    var account_sum: f64 = 0;
    for (result.account) |item| {
        account_sum += item.value;
    }
    try std.testing.expectApproxEqAbs(@as(f64, 142_500), account_sum, 1.0);
}