//! Chart-to-PNG export.
//!
//! The CLI's `--export-chart <path>` flag funnels through this
//! module. Each chart-bearing command (`quote`, `projections`)
//! has a corresponding `export*` function here that:
//!
//!   1. Calls the relevant `renderToSurface` (in `charts/chart.zig` or
//!      `charts/projection_chart.zig`) to draw the chart into a z2d
//!      `Surface`.
//!   2. Calls `z2d.png_exporter.writeToPNGFile` to land the surface
//!      as a PNG file at the user-supplied path.
//!   3. Frees the surface.
//!
//! Default export resolution is 1920x1080 - matches the TUI's
//! `chart_config.max_width`/`max_height` defaults so the exported
//! image has the same fidelity the user sees in the terminal.
//! The TUI's adaptive chart sizing isn't used here because the
//! export target is a file, not a cell grid.
//!
//! Each `export*` takes the `theme.Theme` to render with - the CLI
//! resolves it from `--theme <PATH>` (a `theme.srf`), defaulting to
//! the built-in theme so exports keep the TUI's visual identity unless
//! the user opts into a custom or presentation-friendly palette.

const std = @import("std");
const z2d = @import("z2d");
const zfin = @import("root.zig");
const chart = @import("charts/chart.zig");
const projection_chart = @import("charts/projection_chart.zig");
const line_chart = @import("charts/line_chart.zig");
const projections = @import("analytics/projections.zig");
const forecast = @import("analytics/forecast_evaluation.zig");
const forecast_chart = @import("charts/forecast_chart.zig");
const compare_chart = @import("charts/compare_chart.zig");
const theme = @import("tui/theme.zig");

/// Default PNG export resolution. Matches `charts/chart.zig`'s
/// `ChartConfig.max_width/max_height` defaults so an exported
/// image carries the same fidelity as a maximally-sized TUI
/// chart.
pub const default_width: u32 = 1920;
pub const default_height: u32 = 1080;

/// Export a price+Bollinger+RSI chart for a single symbol, showing the
/// most recent `display_count` candles. The overlays are computed with a
/// warmup lookback (via `chart.computeIndicatorsWarmup`) so they're valid
/// from the first displayed candle. Wraps `renderToSurface` + `writeToPNGFile`.
pub fn exportSymbolChart(
    io: std.Io,
    alloc: std.mem.Allocator,
    candles: []const zfin.Candle,
    display_count: usize,
    th: theme.Theme,
    path: []const u8,
) !void {
    var cached = chart.computeIndicatorsWarmup(alloc, candles, display_count, 20) catch |err| switch (err) {
        error.InsufficientData => return error.InsufficientData,
        else => return err,
    };
    defer cached.deinit(alloc);
    const n = @min(candles.len, display_count);
    const display = candles[candles.len - n ..];

    var rendered = chart.renderToSurface(
        io,
        alloc,
        display,
        null,
        default_width,
        default_height,
        th,
        &cached,
        true,
    ) catch |err| switch (err) {
        error.InsufficientData => return error.InsufficientData,
        else => return err,
    };
    defer rendered.deinit(alloc);

    try z2d.png_exporter.writeToPNGFile(io, rendered.surface, path, .{});
}

/// Export a projection percentile-band chart with optional actuals
/// overlay. Wraps `projection_chart.renderToSurface` +
/// `writeToPNGFile`. `retirement_boundary_year` (pass
/// `ResolvedRetirement.boundaryYear()`) draws the
/// accumulation/distribution divider when set.
pub fn exportProjectionChart(
    io: std.Io,
    alloc: std.mem.Allocator,
    bands: []const projections.YearPercentiles,
    actuals: ?projection_chart.ActualsOverlay,
    retirement_boundary_year: ?u16,
    th: theme.Theme,
    path: []const u8,
) !void {
    var rendered = projection_chart.renderToSurface(
        io,
        alloc,
        bands,
        default_width,
        default_height,
        th,
        actuals,
        true,
        retirement_boundary_year,
    ) catch |err| switch (err) {
        error.InsufficientData => return error.InsufficientData,
        else => return err,
    };
    defer rendered.deinit(alloc);

    try z2d.png_exporter.writeToPNGFile(io, rendered.surface, path, .{});
}

/// Export a single-series portfolio-value timeline as a PNG. Wraps
/// `line_chart.renderToSurface` + `writeToPNGFile`. `baseline` selects
/// whether the y-axis fits the data or anchors at zero.
pub fn exportTimelineChart(
    io: std.Io,
    alloc: std.mem.Allocator,
    points: []const line_chart.LinePoint,
    baseline: line_chart.Baseline,
    th: theme.Theme,
    path: []const u8,
) !void {
    var rendered = line_chart.renderToSurface(
        io,
        alloc,
        points,
        default_width,
        default_height,
        th,
        .{ .baseline = baseline, .axis_labels = true },
    ) catch |err| switch (err) {
        error.InsufficientData => return error.InsufficientData,
        else => return err,
    };
    defer rendered.deinit(alloc);

    try z2d.png_exporter.writeToPNGFile(io, rendered.surface, path, .{});
}

/// Export the convergence forecast chart (years-until-retirement vs.
/// observation date) as a PNG. Wraps
/// `forecast_chart.renderConvergenceToSurface` + `writeToPNGFile`.
pub fn exportConvergenceChart(
    io: std.Io,
    alloc: std.mem.Allocator,
    points: []const forecast.ConvergencePoint,
    th: theme.Theme,
    path: []const u8,
) !void {
    var rendered = forecast_chart.renderConvergenceToSurface(
        io,
        alloc,
        points,
        default_width,
        default_height,
        th,
        true,
    ) catch |err| switch (err) {
        error.InsufficientData => return error.InsufficientData,
        else => return err,
    };
    defer rendered.deinit(alloc);

    try z2d.png_exporter.writeToPNGFile(io, rendered.surface, path, .{});
}

/// Export the return back-test forecast chart (expected vs. realized
/// forward CAGR by anchor) as a PNG. Wraps
/// `forecast_chart.renderBacktestToSurface` + `writeToPNGFile`.
pub fn exportBacktestChart(
    io: std.Io,
    alloc: std.mem.Allocator,
    anchors: []const forecast.BacktestAnchor,
    th: theme.Theme,
    path: []const u8,
) !void {
    var rendered = forecast_chart.renderBacktestToSurface(
        io,
        alloc,
        anchors,
        default_width,
        default_height,
        th,
        true,
    ) catch |err| switch (err) {
        error.InsufficientData => return error.InsufficientData,
        else => return err,
    };
    defer rendered.deinit(alloc);

    try z2d.png_exporter.writeToPNGFile(io, rendered.surface, path, .{});
}

/// Export the `--vs` projection comparison overlay - two percentile-
/// band envelopes ("then" and "now") on one chart. Wraps
/// `compare_chart.renderToSurface` + `writeToPNGFile`.
pub fn exportCompareChart(
    io: std.Io,
    alloc: std.mem.Allocator,
    then_bands: []const projections.YearPercentiles,
    now_bands: []const projections.YearPercentiles,
    th: theme.Theme,
    path: []const u8,
) !void {
    var rendered = compare_chart.renderToSurface(
        io,
        alloc,
        then_bands,
        now_bands,
        default_width,
        default_height,
        th,
        true,
    ) catch |err| switch (err) {
        error.InsufficientData => return error.InsufficientData,
        else => return err,
    };
    defer rendered.deinit(alloc);

    try z2d.png_exporter.writeToPNGFile(io, rendered.surface, path, .{});
}

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

test "exportSymbolChart writes a non-empty PNG file" {
    const Date = @import("Date.zig");
    const alloc = std.testing.allocator;
    const io = std.testing.io;

    // Minimum candle count (renderToSurface requires >= 20)
    var candles: [25]zfin.Candle = undefined;
    for (0..25) |i| {
        const price: f64 = 100.0 + @as(f64, @floatFromInt(i));
        candles[i] = .{
            .date = Date.fromYmd(2024, 1, 2).addDays(@intCast(i)),
            .open = price,
            .high = price + 1,
            .low = price - 1,
            .close = price,
            .adj_close = price,
            .volume = 1000,
        };
    }

    var tmp = std.testing.tmpDir(.{});
    defer tmp.cleanup();
    var path_buf: [std.fs.max_path_bytes]u8 = undefined;
    const dir_len = try tmp.dir.realPathFile(io, ".", &path_buf);
    const dir_path = path_buf[0..dir_len];
    const path = try std.fs.path.join(alloc, &.{ dir_path, "test_export_symbol.png" });
    defer alloc.free(path);

    try exportSymbolChart(io, alloc, &candles, 60, theme.default_theme, path);

    // Verify the file exists, starts with the PNG magic, and is
    // big enough to plausibly contain a chart (not just headers).
    var file = try tmp.dir.openFile(io, "test_export_symbol.png", .{});
    defer file.close(io);
    const size = (try file.stat(io)).size;
    try std.testing.expect(size > 1024); // arbitrary lower bound

    var magic: [8]u8 = undefined;
    var reader = file.reader(io, &.{});
    _ = try reader.interface.readSliceShort(&magic);
    try std.testing.expectEqualSlices(u8, "\x89PNG\x0D\x0A\x1A\x0A", &magic);
}

test "exportSymbolChart returns InsufficientData on too-few candles" {
    const Date = @import("Date.zig");
    const alloc = std.testing.allocator;
    const io = std.testing.io;

    var candles: [10]zfin.Candle = undefined;
    for (0..10) |i| {
        candles[i] = .{
            .date = Date.fromYmd(2024, 1, 2).addDays(@intCast(i)),
            .open = 100,
            .high = 100,
            .low = 100,
            .close = 100,
            .adj_close = 100,
            .volume = 0,
        };
    }

    var tmp = std.testing.tmpDir(.{});
    defer tmp.cleanup();
    var path_buf: [std.fs.max_path_bytes]u8 = undefined;
    const dir_len = try tmp.dir.realPathFile(io, ".", &path_buf);
    const dir_path = path_buf[0..dir_len];
    const path = try std.fs.path.join(alloc, &.{ dir_path, "test_export_symbol_insufficient.png" });
    defer alloc.free(path);

    try std.testing.expectError(
        error.InsufficientData,
        exportSymbolChart(io, alloc, &candles, 60, theme.default_theme, path),
    );
}

test "exportProjectionChart writes a non-empty PNG file" {
    const alloc = std.testing.allocator;
    const io = std.testing.io;

    // Synthetic 11-year horizon: bands grow linearly, all
    // percentiles spread around p50.
    var bands: [11]projections.YearPercentiles = undefined;
    for (0..11) |i| {
        const base: f64 = 100_000.0 * (1.0 + 0.07 * @as(f64, @floatFromInt(i)));
        bands[i] = .{
            .year = @intCast(i),
            .p10 = base * 0.6,
            .p25 = base * 0.8,
            .p50 = base,
            .p75 = base * 1.2,
            .p90 = base * 1.5,
        };
    }

    var tmp = std.testing.tmpDir(.{});
    defer tmp.cleanup();
    var path_buf: [std.fs.max_path_bytes]u8 = undefined;
    const dir_len = try tmp.dir.realPathFile(io, ".", &path_buf);
    const dir_path = path_buf[0..dir_len];
    const path = try std.fs.path.join(alloc, &.{ dir_path, "test_export_projection.png" });
    defer alloc.free(path);

    try exportProjectionChart(io, alloc, &bands, null, null, theme.default_theme, path);

    var file = try tmp.dir.openFile(io, "test_export_projection.png", .{});
    defer file.close(io);
    const size = (try file.stat(io)).size;
    try std.testing.expect(size > 1024);

    var magic: [8]u8 = undefined;
    var reader = file.reader(io, &.{});
    _ = try reader.interface.readSliceShort(&magic);
    try std.testing.expectEqualSlices(u8, "\x89PNG\x0D\x0A\x1A\x0A", &magic);
}

test "exportProjectionChart returns InsufficientData with single band" {
    const alloc = std.testing.allocator;
    const io = std.testing.io;

    var bands: [1]projections.YearPercentiles = .{.{
        .year = 0,
        .p10 = 100,
        .p25 = 110,
        .p50 = 120,
        .p75 = 130,
        .p90 = 140,
    }};

    var tmp = std.testing.tmpDir(.{});
    defer tmp.cleanup();
    var path_buf: [std.fs.max_path_bytes]u8 = undefined;
    const dir_len = try tmp.dir.realPathFile(io, ".", &path_buf);
    const dir_path = path_buf[0..dir_len];
    const path = try std.fs.path.join(alloc, &.{ dir_path, "test_export_projection_insufficient.png" });
    defer alloc.free(path);

    try std.testing.expectError(
        error.InsufficientData,
        exportProjectionChart(io, alloc, &bands, null, null, theme.default_theme, path),
    );
}

test "exportTimelineChart writes a non-empty PNG file" {
    const Date = @import("Date.zig");
    const alloc = std.testing.allocator;
    const io = std.testing.io;

    var points: [12]line_chart.LinePoint = undefined;
    for (0..12) |i| {
        points[i] = .{
            .date = Date.fromYmd(2025, 1, 1).addDays(@intCast(i * 30)),
            .value = 1_000_000.0 + 25_000.0 * @as(f64, @floatFromInt(i)),
        };
    }

    var tmp = std.testing.tmpDir(.{});
    defer tmp.cleanup();
    var path_buf: [std.fs.max_path_bytes]u8 = undefined;
    const dir_len = try tmp.dir.realPathFile(io, ".", &path_buf);
    const dir_path = path_buf[0..dir_len];
    const path = try std.fs.path.join(alloc, &.{ dir_path, "test_export_timeline.png" });
    defer alloc.free(path);

    try exportTimelineChart(io, alloc, &points, .fit, theme.default_theme, path);

    var file = try tmp.dir.openFile(io, "test_export_timeline.png", .{});
    defer file.close(io);
    const size = (try file.stat(io)).size;
    try std.testing.expect(size > 1024);

    var magic: [8]u8 = undefined;
    var reader = file.reader(io, &.{});
    _ = try reader.interface.readSliceShort(&magic);
    try std.testing.expectEqualSlices(u8, "\x89PNG\x0D\x0A\x1A\x0A", &magic);
}

test "exportTimelineChart returns InsufficientData with a single point" {
    const Date = @import("Date.zig");
    const alloc = std.testing.allocator;
    const io = std.testing.io;

    var points: [1]line_chart.LinePoint = .{.{ .date = Date.fromYmd(2025, 1, 1), .value = 1_000_000 }};

    var tmp = std.testing.tmpDir(.{});
    defer tmp.cleanup();
    var path_buf: [std.fs.max_path_bytes]u8 = undefined;
    const dir_len = try tmp.dir.realPathFile(io, ".", &path_buf);
    const dir_path = path_buf[0..dir_len];
    const path = try std.fs.path.join(alloc, &.{ dir_path, "test_export_timeline_insufficient.png" });
    defer alloc.free(path);

    try std.testing.expectError(
        error.InsufficientData,
        exportTimelineChart(io, alloc, &points, .fit, theme.default_theme, path),
    );
}

test "exportConvergenceChart writes a non-empty PNG file" {
    const Date = @import("Date.zig");
    const alloc = std.testing.allocator;
    const io = std.testing.io;

    const points = [_]forecast.ConvergencePoint{
        .{ .observation_date = Date.fromYmd(2020, 1, 1), .projected_date = Date.fromYmd(2032, 1, 1), .years_until_retirement = 12.0, .reached = false },
        .{ .observation_date = Date.fromYmd(2022, 1, 1), .projected_date = Date.fromYmd(2031, 1, 1), .years_until_retirement = 9.0, .reached = false },
        .{ .observation_date = Date.fromYmd(2025, 1, 1), .projected_date = Date.fromYmd(2030, 1, 1), .years_until_retirement = 5.0, .reached = false },
    };

    var tmp = std.testing.tmpDir(.{});
    defer tmp.cleanup();
    var path_buf: [std.fs.max_path_bytes]u8 = undefined;
    const dir_len = try tmp.dir.realPathFile(io, ".", &path_buf);
    const dir_path = path_buf[0..dir_len];
    const path = try std.fs.path.join(alloc, &.{ dir_path, "test_export_convergence.png" });
    defer alloc.free(path);

    try exportConvergenceChart(io, alloc, &points, theme.default_theme, path);

    var file = try tmp.dir.openFile(io, "test_export_convergence.png", .{});
    defer file.close(io);
    const size = (try file.stat(io)).size;
    try std.testing.expect(size > 1024);

    var magic: [8]u8 = undefined;
    var reader = file.reader(io, &.{});
    _ = try reader.interface.readSliceShort(&magic);
    try std.testing.expectEqualSlices(u8, "\x89PNG\x0D\x0A\x1A\x0A", &magic);
}

test "exportConvergenceChart returns InsufficientData with a single point" {
    const Date = @import("Date.zig");
    const alloc = std.testing.allocator;
    const io = std.testing.io;

    const points = [_]forecast.ConvergencePoint{
        .{ .observation_date = Date.fromYmd(2020, 1, 1), .projected_date = Date.fromYmd(2030, 1, 1), .years_until_retirement = 10.0, .reached = false },
    };

    var tmp = std.testing.tmpDir(.{});
    defer tmp.cleanup();
    var path_buf: [std.fs.max_path_bytes]u8 = undefined;
    const dir_len = try tmp.dir.realPathFile(io, ".", &path_buf);
    const dir_path = path_buf[0..dir_len];
    const path = try std.fs.path.join(alloc, &.{ dir_path, "test_export_convergence_insufficient.png" });
    defer alloc.free(path);

    try std.testing.expectError(
        error.InsufficientData,
        exportConvergenceChart(io, alloc, &points, theme.default_theme, path),
    );
}

test "exportBacktestChart writes a non-empty PNG file" {
    const Date = @import("Date.zig");
    const alloc = std.testing.allocator;
    const io = std.testing.io;

    const anchors = [_]forecast.BacktestAnchor{
        .{ .anchor_date = Date.fromYmd(2016, 1, 1), .expected = 0.07, .realized_1y = 0.12, .realized_3y = 0.09, .realized_5y = 0.08 },
        .{ .anchor_date = Date.fromYmd(2019, 1, 1), .expected = 0.08, .realized_1y = 0.18, .realized_3y = 0.10, .realized_5y = null },
        .{ .anchor_date = Date.fromYmd(2022, 1, 1), .expected = 0.06, .realized_1y = -0.05, .realized_3y = null, .realized_5y = null },
    };

    var tmp = std.testing.tmpDir(.{});
    defer tmp.cleanup();
    var path_buf: [std.fs.max_path_bytes]u8 = undefined;
    const dir_len = try tmp.dir.realPathFile(io, ".", &path_buf);
    const dir_path = path_buf[0..dir_len];
    const path = try std.fs.path.join(alloc, &.{ dir_path, "test_export_backtest.png" });
    defer alloc.free(path);

    try exportBacktestChart(io, alloc, &anchors, theme.default_theme, path);

    var file = try tmp.dir.openFile(io, "test_export_backtest.png", .{});
    defer file.close(io);
    const size = (try file.stat(io)).size;
    try std.testing.expect(size > 1024);

    var magic: [8]u8 = undefined;
    var reader = file.reader(io, &.{});
    _ = try reader.interface.readSliceShort(&magic);
    try std.testing.expectEqualSlices(u8, "\x89PNG\x0D\x0A\x1A\x0A", &magic);
}

test "exportBacktestChart returns InsufficientData with a single anchor" {
    const Date = @import("Date.zig");
    const alloc = std.testing.allocator;
    const io = std.testing.io;

    const anchors = [_]forecast.BacktestAnchor{
        .{ .anchor_date = Date.fromYmd(2020, 1, 1), .expected = 0.10, .realized_1y = null, .realized_3y = null, .realized_5y = null },
    };

    var tmp = std.testing.tmpDir(.{});
    defer tmp.cleanup();
    var path_buf: [std.fs.max_path_bytes]u8 = undefined;
    const dir_len = try tmp.dir.realPathFile(io, ".", &path_buf);
    const dir_path = path_buf[0..dir_len];
    const path = try std.fs.path.join(alloc, &.{ dir_path, "test_export_backtest_insufficient.png" });
    defer alloc.free(path);

    try std.testing.expectError(
        error.InsufficientData,
        exportBacktestChart(io, alloc, &anchors, theme.default_theme, path),
    );
}

test "exportCompareChart writes a non-empty PNG file" {
    const alloc = std.testing.allocator;
    const io = std.testing.io;

    var then_bands: [11]projections.YearPercentiles = undefined;
    var now_bands: [11]projections.YearPercentiles = undefined;
    for (0..11) |i| {
        const t: f64 = 1_000_000.0 * (1.0 + 0.05 * @as(f64, @floatFromInt(i)));
        const n: f64 = 1_200_000.0 * (1.0 + 0.06 * @as(f64, @floatFromInt(i)));
        then_bands[i] = .{ .year = @intCast(i), .p10 = t * 0.6, .p25 = t * 0.8, .p50 = t, .p75 = t * 1.2, .p90 = t * 1.5 };
        now_bands[i] = .{ .year = @intCast(i), .p10 = n * 0.6, .p25 = n * 0.8, .p50 = n, .p75 = n * 1.2, .p90 = n * 1.5 };
    }

    var tmp = std.testing.tmpDir(.{});
    defer tmp.cleanup();
    var path_buf: [std.fs.max_path_bytes]u8 = undefined;
    const dir_len = try tmp.dir.realPathFile(io, ".", &path_buf);
    const dir_path = path_buf[0..dir_len];
    const path = try std.fs.path.join(alloc, &.{ dir_path, "test_export_compare.png" });
    defer alloc.free(path);

    try exportCompareChart(io, alloc, &then_bands, &now_bands, theme.default_theme, path);

    var file = try tmp.dir.openFile(io, "test_export_compare.png", .{});
    defer file.close(io);
    const size = (try file.stat(io)).size;
    try std.testing.expect(size > 1024);

    var magic: [8]u8 = undefined;
    var reader = file.reader(io, &.{});
    _ = try reader.interface.readSliceShort(&magic);
    try std.testing.expectEqualSlices(u8, "\x89PNG\x0D\x0A\x1A\x0A", &magic);
}

test "exportCompareChart returns InsufficientData with a single-year side" {
    const alloc = std.testing.allocator;
    const io = std.testing.io;

    const then_bands = [_]projections.YearPercentiles{.{ .year = 0, .p10 = 1, .p25 = 2, .p50 = 3, .p75 = 4, .p90 = 5 }};
    var now_bands: [3]projections.YearPercentiles = undefined;
    for (0..3) |i| now_bands[i] = .{ .year = @intCast(i), .p10 = 1, .p25 = 2, .p50 = 3, .p75 = 4, .p90 = 5 };

    var tmp = std.testing.tmpDir(.{});
    defer tmp.cleanup();
    var path_buf: [std.fs.max_path_bytes]u8 = undefined;
    const dir_len = try tmp.dir.realPathFile(io, ".", &path_buf);
    const dir_path = path_buf[0..dir_len];
    const path = try std.fs.path.join(alloc, &.{ dir_path, "test_export_compare_insufficient.png" });
    defer alloc.free(path);

    try std.testing.expectError(
        error.InsufficientData,
        exportCompareChart(io, alloc, &then_bands, &now_bands, theme.default_theme, path),
    );
}