/// 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;

/// 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,
};

/// 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);
        }
        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";
    }
};

/// Parse an accounts.srf file into an AccountMap.
/// Each record has: account::<NAME>,tax_type::<TYPE>
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);
        }
        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,
        });
    }

    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.
pub fn analyzePortfolio(
    allocator: std.mem.Allocator,
    allocations: []const Allocation,
    classifications: ClassificationMap,
    portfolio: Portfolio,
    total_portfolio_value: f64,
    account_map: ?AccountMap,
) !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 lookup from allocations (for lot-level valuation)
    var price_lookup = std.StringHashMap(f64).init(allocator);
    defer price_lookup.deinit();
    for (allocations) |alloc| {
        price_lookup.put(alloc.symbol, alloc.current_price) catch {};
    }

    // Account breakdown from individual lots (avoids "Multiple" aggregation issue)
    for (portfolio.lots) |lot| {
        if (!lot.isOpen()) continue;
        const acct = lot.account orelse continue;
        const value: f64 = switch (lot.security_type) {
            .stock => blk: {
                const price = price_lookup.get(lot.priceSymbol()) orelse lot.open_price;
                break :blk lot.shares * 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 "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);
}