//! Colour themes: the Theme type, the curated and generated ring, chrome
//! colours and their animation, theme files, and switching themes at runtime.
const pardes = @import("pardes.zig");
const tagline = @import("tagline.zig");
const panes = @import("panes.zig");
const std = @import("std");
const layout = @import("layout.zig");
const animation = @import("animation.zig");
const Color = @import("surface.zig").Color;
const FontRole = @import("surface.zig").FontRole;
const config = @import("config.zig");
const pdf_enabled = panes.Pdf.enabled;
const platform = pardes.platform;
const theme_animation = @import("pardes_config").theme_animation;
const hosted = pardes.hosted;
const MAX_PANES = pardes.MAX_PANES;
const BOX_H = pardes.BOX_H;
const Pardes = pardes.Pardes;

pub fn mix(a: [3]u8, b: [3]u8) [3]u8 {
    var out: [3]u8 = undefined;
    for (&out, a, b) |*c, x, y| c.* = @intCast((@as(u16, x) + y) / 2);
    return out;
}

pub const Theme = struct {
    name: []const u8,
    bg: ?[3]u8,
    fg: ?[3]u8,
    sel_bg: [3]u8,
    sel_fg: [3]u8,
    tag_bg: [3]u8,
    tag_fg: [3]u8,
    box: [3]u8, // move box, focused pane
    box_dim: [3]u8, // move box, everything else
    kw: [3]u8,
    str: [3]u8,
    num: [3]u8,
    comment: [3]u8,
    lineno: [3]u8,
    scroll_track: [3]u8,
    scroll_thumb: [3]u8,
    palette: ?[16][3]u8,

    // Pardes UI roles. Optional so existing ThemeFile documents and imported
    // editor palettes keep working; ChromeTheme resolves their legacy defaults.
    tag_active_bg: ?[3]u8 = null,
    tag_active_fg: ?[3]u8 = null,
    /// Filename/output-name accent, also used by the Tty command.
    tag_name_fg: ?[3]u8 = null,
    /// Active tint; absence preserves the shared name tint or active tag ink.
    tag_active_name_fg: ?[3]u8 = null,
    /// Column grips stay distinct from pane grips in both focus states.
    column_box: ?[3]u8 = null,
    column_box_dim: ?[3]u8 = null,
    border: ?[3]u8 = null,
    search_bg: ?[3]u8 = null,
    search_fg: ?[3]u8 = null,
    diagnostic_error: ?[3]u8 = null,
    diagnostic_warning: ?[3]u8 = null,
    diagnostic_info: ?[3]u8 = null,
    diagnostic_hint: ?[3]u8 = null,
    // The current line number is a quiet foreground cue, not a tag-colored
    // background block. Older themes fall back to their normal gutter ink.
    lineno_active: ?[3]u8 = null,
};

const curated = struct {
    pub const orchard = @import("themes/orchard.zig");
    pub const dusk = @import("themes/dusk.zig");
    pub const ink = @import("themes/ink.zig");
    pub const paper = @import("themes/paper.zig");
    pub const daybreak = @import("themes/daybreak.zig");
    pub const atelier = @import("themes/atelier.zig");
    pub const forge = @import("themes/forge.zig");
    pub const lagoon = @import("themes/lagoon.zig");
    pub const solarium = @import("themes/solarium.zig");
    pub const spectrum = @import("themes/spectrum.zig");
    pub const harvest = @import("themes/harvest.zig");
    pub const clay = @import("themes/clay.zig");
    pub const forge_black = @import("themes/forge_black.zig");
    pub const forge_soft = @import("themes/forge_soft.zig");
    pub const orchard_black = @import("themes/orchard_black.zig");
    pub const helix = @import("themes/helix.zig");
    pub const dark = @import("themes/dark.zig");
    pub const acme = @import("themes/acme.zig");
};

fn fold(comptime C: type) [@typeInfo(C).@"struct".decls.len]Theme {
    comptime {
        @setEvalBranchQuota(400000);
        var out: [@typeInfo(C).@"struct".decls.len]Theme = undefined;
        for (@typeInfo(C).@"struct".decls, 0..) |d, i| {
            var t: Theme = undefined;
            const source = @field(C, d.name).theme;
            for (@typeInfo(Theme).@"struct".fields) |f| {
                @field(t, f.name) = if (@hasField(@TypeOf(source), f.name))
                    @field(source, f.name)
                else if (f.default_value_ptr) |ptr|
                    @as(*const f.type, @ptrCast(@alignCast(ptr))).*
                else
                    @compileError("theme " ++ d.name ++ " is missing " ++ f.name);
            }
            out[i] = t;
        }
        return out;
    }
}

pub const themes = fold(curated) ++ fold(@import("generated_themes"));

/// Original and classic-inspired Pardes palettes precede retained imports.
pub const native_theme_count = 15;

fn themeContrast(a: [3]u8, b: [3]u8) f64 {
    var luminance: [2]f64 = .{ 0, 0 };
    for ([2][3]u8{ a, b }, 0..) |rgb, i| {
        for (rgb, [3]f64{ 0.2126, 0.7152, 0.0722 }) |channel, weight| {
            const srgb = @as(f64, @floatFromInt(channel)) / 255;
            const linear = if (srgb <= 0.04045) srgb / 12.92 else std.math.pow(f64, (srgb + 0.055) / 1.055, 2.4);
            luminance[i] += weight * linear;
        }
    }
    return (@max(luminance[0], luminance[1]) + 0.05) / (@min(luminance[0], luminance[1]) + 0.05);
}

comptime {
    if (themes.len > std.math.maxInt(u16) + 1)
        @compileError("runtime config theme index no longer fits u16");
}

comptime {
    @setEvalBranchQuota(20000);
    const ours = fold(curated).len;
    for (themes[0..ours]) |c| for (themes[ours..]) |g| if (std.mem.eql(u8, c.name, g.name))
        @compileError("theme name \"" ++ c.name ++ "\" is both ours and generated; rename the vendored source");
}

pub const ChromeTheme = struct {
    tag_bg: [3]u8,
    tag_fg: [3]u8,
    tag_active_bg: [3]u8,
    tag_active_fg: [3]u8,
    tag_name_fg: [3]u8,
    tag_active_name_fg: [3]u8,
    border: [3]u8,
    search_bg: [3]u8,
    search_fg: [3]u8,
    diagnostic_error: [3]u8,
    diagnostic_warning: [3]u8,
    diagnostic_info: [3]u8,
    diagnostic_hint: [3]u8,
    box: [3]u8,
    box_dim: [3]u8,
    column_box: [3]u8,
    column_box_dim: [3]u8,
    lineno: [3]u8,
    scroll_track: [3]u8,
    scroll_thumb: [3]u8,

    pub fn fromTheme(th: *const Theme) ChromeTheme {
        return .{
            .tag_bg = th.tag_bg,
            .tag_fg = th.tag_fg,
            .tag_active_bg = th.tag_active_bg orelse th.tag_bg,
            .tag_active_fg = th.tag_active_fg orelse th.tag_fg,
            .tag_name_fg = th.tag_name_fg orelse th.tag_fg,
            .tag_active_name_fg = th.tag_active_name_fg orelse (th.tag_name_fg orelse (th.tag_active_fg orelse th.tag_fg)),
            .border = th.border orelse th.scroll_track,
            .search_bg = th.search_bg orelse th.sel_bg,
            .search_fg = th.search_fg orelse th.sel_fg,
            .diagnostic_error = th.diagnostic_error orelse (th.fg orelse th.tag_fg),
            .diagnostic_warning = th.diagnostic_warning orelse (th.fg orelse th.tag_fg),
            .diagnostic_info = th.diagnostic_info orelse (th.fg orelse th.tag_fg),
            .diagnostic_hint = th.diagnostic_hint orelse (th.fg orelse th.tag_fg),
            .box = th.box,
            .box_dim = th.box_dim,
            .column_box = th.column_box orelse th.num,
            .column_box_dim = th.column_box_dim orelse mix(th.column_box orelse th.num, th.tag_bg),
            .lineno = th.lineno,
            .scroll_track = th.scroll_track,
            .scroll_thumb = th.scroll_thumb,
        };
    }

    pub fn interpolate(from: ChromeTheme, to: ChromeTheme, step: u16, steps: u16) ChromeTheme {
        var out: ChromeTheme = undefined;
        inline for (@typeInfo(ChromeTheme).@"struct".fields) |field|
            @field(out, field.name) = animation.Animation.interpolateRgb(@field(from, field.name), @field(to, field.name), step, steps);
        return out;
    }
};

pub const ChromeAnimation = if (theme_animation)
    animation.Animation.Transition(ChromeTheme)
else
    animation.Animation.Immediate(ChromeTheme);

pub const initial_chrome = ChromeTheme.fromTheme(&themes[0]);

fn nextThemeFileGeneration(p: *Pardes) u32 {
    p.theme_file_generation +%= 1;
    if (p.theme_file_generation == 0) p.theme_file_generation = 1;
    return p.theme_file_generation;
}

pub fn requestThemeFile(p: *Pardes, id: usize, argument: []const u8) void {
    if (comptime !hosted) return;
    const input = std.mem.trim(u8, argument, " \t\r\n");
    if (input.len == 0 or !std.mem.endsWith(u8, input, ".zon")) {
        p.reportError(id, "theme file", error.InvalidThemePath);
        return;
    }

    const absolute = std.fs.path.isAbsolute(input);
    if (!absolute and p.opts.config_dir == null) {
        p.reportError(id, "theme file", error.NoConfigDirectory);
        return;
    }

    var joined: [4095]u8 = undefined;
    const resolved = if (absolute) input else path: {
        const dir = p.opts.config_dir.?;
        const separator = std.Io.Dir.path.sep;
        const needs_separator = dir.len > 0 and dir[dir.len - 1] != separator;
        const len = dir.len + @intFromBool(needs_separator) + input.len;
        if (len > joined.len) {
            p.reportError(id, "theme file", error.PathTooLong);
            return;
        }
        @memcpy(joined[0..dir.len], dir);
        var at = dir.len;
        if (needs_separator) {
            joined[at] = separator;
            at += 1;
        }
        @memcpy(joined[at..][0..input.len], input);
        break :path joined[0..len];
    };
    if (!p.theme_file_path.set(resolved)) {
        p.reportError(id, "theme file", error.PathTooLong);
        return;
    }
    p.theme_file_pane = @intCast(@min(id, MAX_PANES - 1));
    const generation = nextThemeFileGeneration(p);
    p.emit(.{ .theme_file = .{ .generation = generation, .on = true } });
}

pub const ThemeFileRequest = struct {
    path: []const u8,
    pane: u8,
};

/// Borrow the current request while a native host performs its synchronous
/// read. A later command invalidates an already-queued generation.
pub fn themeFileRequest(p: *const Pardes, generation: u32) ?ThemeFileRequest {
    if (generation == 0 or generation != p.theme_file_generation) return null;
    const path = p.theme_file_path.get();
    if (path.len == 0) return null;
    return .{ .path = path, .pane = p.theme_file_pane };
}

pub fn failThemeFile(p: *Pardes, generation: u32, err: anyerror) void {
    const request = themeFileRequest(p, generation) orelse return;
    p.reportError(request.pane, "theme file", err);
}

pub fn loadThemeFile(p: *Pardes, generation: u32, bytes: []const u8, animate: bool) bool {
    // ZON's generated field dispatch grows with the complete theme schema.
    @setEvalBranchQuota(10000);
    const request = themeFileRequest(p, generation) orelse return false;
    if (bytes.len > 1024 * 1024) {
        p.reportError(request.pane, "theme file", error.ThemeFileTooLarge);
        return false;
    }
    const source = p.gpa.dupeZ(u8, bytes) catch |err| {
        p.reportError(request.pane, "theme file", err);
        return false;
    };
    defer p.gpa.free(source);
    var diagnostics: std.zon.parse.Diagnostics = .{};
    defer diagnostics.deinit(p.gpa);
    const parsed = std.zon.parse.fromSliceAlloc(Theme, p.gpa, source, &diagnostics, .{}) catch |err| {
        p.reportError(request.pane, "theme file", err);
        return false;
    };
    if (parsed.name.len == 0 or parsed.name.len > 255) {
        std.zon.parse.free(p.gpa, parsed);
        p.reportError(request.pane, "theme file", error.InvalidThemeName);
        return false;
    }

    const target_chrome = ChromeTheme.fromTheme(&parsed);
    if (animate and p.animate_theme_changes)
        p.chrome_animation.retarget(target_chrome)
    else
        p.chrome_animation.snap(target_chrome);
    const old = p.custom_theme;
    p.custom_theme = parsed;
    if (old) |theme_value| std.zon.parse.free(p.gpa, theme_value);
    invalidateThemeDependentRasters(p);
    _ = p.scratch.reset(.retain_capacity);
    p.sync();
    return true;
}

pub fn finishThemeInitialization(p: *Pardes) void {
    p.chrome_animation.snap(ChromeTheme.fromTheme(p.theme()));
    p.animate_theme_changes = true;
}

fn invalidateThemeDependentRasters(p: *Pardes) void {
    if (comptime pdf_enabled) for (p.panes) |slot| {
        const pane = slot orelse continue;
        const pv = &(pane.pdf orelse continue);
        if (pv.tint != .disabled) pv.invalidateAllRasters();
    };
}

pub fn setThemeIndex(p: *Pardes, index: usize) void {
    if (index >= themes.len or
        (p.custom_theme == null and p.theme_file_path.get().len == 0 and
            index == @as(usize, p.settings.theme))) return;
    const target_chrome = ChromeTheme.fromTheme(&themes[index]);
    if (p.animate_theme_changes)
        p.chrome_animation.retarget(target_chrome)
    else
        p.chrome_animation.snap(target_chrome);
    if (p.custom_theme) |theme_value| {
        p.custom_theme = null;
        std.zon.parse.free(p.gpa, theme_value);
    }
    if (p.theme_file_path.get().len > 0) {
        p.theme_file_path.clear();
        const generation = nextThemeFileGeneration(p);
        p.emit(.{ .theme_file = .{ .generation = generation, .on = false } });
    }
    p.settings.theme = @intCast(index);
    invalidateThemeDependentRasters(p);
}

test "ThemeFile parses ZON atomically and Theme returns to the compiled ring" {
    if (platform == .web) return;
    const p = try Pardes.init(std.testing.allocator, .{
        .tty_only = true,
        .config_dir = "/tmp/pardes-config",
    });
    defer p.deinit();
    while (p.nextEffect()) |_| {}

    requestThemeFile(p, 0, "themes/mine.zon");
    const request_effect = while (p.nextEffect()) |effect| switch (effect) {
        .theme_file => |request| break request,
        else => {},
    } else return error.MissingThemeFileEffect;
    try std.testing.expect(request_effect.on);
    const request = themeFileRequest(p, request_effect.generation) orelse
        return error.MissingThemeFileRequest;
    try std.testing.expectEqualStrings("/tmp/pardes-config/themes/mine.zon", request.path);

    var custom = themes[0];
    custom.name = "mine";
    custom.bg = .{ 1, 2, 3 };
    custom.tag_bg = .{ 4, 5, 6 };
    var encoded: std.Io.Writer.Allocating = .init(std.testing.allocator);
    defer encoded.deinit();
    try std.zon.stringify.serialize(custom, .{ .whitespace = true }, &encoded.writer);
    try std.testing.expect(loadThemeFile(p, request_effect.generation, encoded.written(), false));
    try std.testing.expectEqualStrings("mine", p.theme().name);
    try std.testing.expectEqual(@as(?[3]u8, .{ 1, 2, 3 }), p.theme().bg);
    try std.testing.expectEqual(ChromeTheme.fromTheme(p.theme()), p.chromeTheme().*);

    // A half-written save is rejected without disturbing the last good value.
    try std.testing.expect(!loadThemeFile(p, request_effect.generation, ".{ .name = ", true));
    try std.testing.expectEqualStrings("mine", p.theme().name);
    try std.testing.expectEqual(@as(?[3]u8, .{ 1, 2, 3 }), p.theme().bg);

    setThemeIndex(p, 0);
    try std.testing.expectEqualStrings(themes[0].name, p.theme().name);
    try std.testing.expect(themeFileRequest(p, request_effect.generation) == null);
    const stop = while (p.nextEffect()) |effect| switch (effect) {
        .theme_file => |theme_file| break theme_file,
        else => {},
    } else return error.MissingThemeFileStop;
    try std.testing.expect(!stop.on);
}

test "runtime theme changes animate chrome and retarget without a jump" {
    const p = try Pardes.init(std.testing.allocator, .{ .tty_only = true });
    defer p.deinit();
    const first = p.chromeTheme().*;
    try std.testing.expect(!p.animationActive());

    const dark_index = for (themes, 0..) |th, i| {
        if (std.mem.eql(u8, th.name, "dark")) break i;
    } else return error.MissingDarkTheme;
    const acme_index = for (themes, 0..) |th, i| {
        if (std.mem.eql(u8, th.name, "acme")) break i;
    } else return error.MissingAcmeTheme;

    setThemeIndex(p, dark_index);
    // Target semantics are immediate, while the displayed chrome begins at
    // the exact previous frame.
    try std.testing.expectEqualStrings("dark", p.theme().name);
    try std.testing.expectEqual(first, p.chromeTheme().*);
    try std.testing.expect(p.animationActive());
    p.update(.tick);
    p.update(.tick);
    p.update(.tick);
    const midflight = p.chromeTheme().*;
    try std.testing.expect(!std.meta.eql(first, midflight));

    setThemeIndex(p, acme_index);
    try std.testing.expectEqualStrings("acme", p.theme().name);
    try std.testing.expectEqual(midflight, p.chromeTheme().*);
    try std.testing.expect(p.animationActive());
    for (0..animation.Animation.transition_steps) |_| p.update(.tick);
    try std.testing.expect(!p.animationActive());
    try std.testing.expectEqual(ChromeTheme.fromTheme(p.theme()), p.chromeTheme().*);
    // Extra ticks are inert at the exact endpoint.
    p.update(.tick);
    try std.testing.expectEqual(ChromeTheme.fromTheme(p.theme()), p.chromeTheme().*);
}

test "render uses target content colors while chrome is in flight" {
    const p = try Pardes.init(std.testing.allocator, .{ .tty_only = true, .cols = 40, .rows = 12 });
    defer p.deinit();
    const source_chrome = p.chromeTheme().*;
    const acme_index = for (themes, 0..) |th, i| {
        if (std.mem.eql(u8, th.name, "acme")) break i;
    } else return error.MissingAcmeTheme;
    setThemeIndex(p, acme_index);

    var frame = std.heap.ArenaAllocator.init(std.testing.allocator);
    defer frame.deinit();
    const surface = try p.render(frame.allocator());
    // The anchored topbar has not advanced from its source frame.
    try std.testing.expectEqual(
        Color{ .rgb = source_chrome.tag_bg },
        surface.at(0, 0).style.bg,
    );
    const topbar_cell = surface.at(0, 0);
    try std.testing.expect(!std.mem.eql(u8, topbar_cell.grapheme(), " "));
    try std.testing.expectEqual(FontRole.tagline, topbar_cell.style.font_role);
    const r = p.rects[0];
    const tag_cell = find_tag_cell: {
        var x = r.x + config.GUTTER;
        while (x < r.x + r.w) : (x += 1) {
            const cell = surface.at(x, r.y);
            if (!std.mem.eql(u8, cell.grapheme(), " ")) break :find_tag_cell cell;
        }
        return error.MissingTagText;
    };
    try std.testing.expectEqual(FontRole.tagline, tag_cell.style.font_role);
    try std.testing.expectEqual(FontRole.tagline, surface.at(r.x, r.y).style.font_role);
    try std.testing.expectEqual(FontRole.tagline, surface.at(r.x + r.w - 1, r.y).style.font_role);
    // The document/terminal page does not ride the chrome animation: acme's
    // target background is already present in the same render.
    const body = surface.at(r.x + r.w - 1, r.y + r.h - 1);
    try std.testing.expectEqual(FontRole.body, body.style.font_role);
    try std.testing.expectEqual(
        Color{ .rgb = p.theme().bg.? },
        body.style.bg,
    );
    try std.testing.expect(p.animationActive());
}

test "native themes keep text and UI roles readable on their own surfaces" {
    const names = [_][]const u8{ "orchard", "dusk", "ink", "paper", "daybreak", "atelier", "forge", "lagoon", "solarium", "spectrum", "harvest", "clay", "forge_black", "forge_soft", "orchard_black" };
    try std.testing.expectEqual(names.len, native_theme_count);
    for (themes[0..names.len], names) |th, name| {
        try std.testing.expectEqualStrings(name, th.name);
        const chrome = ChromeTheme.fromTheme(&th);
        const minimum: f64 = if (std.mem.eql(u8, name, "ink") or std.mem.eql(u8, name, "daybreak")) 7 else 4.5;
        const text_colors = [_][3]u8{
            th.fg.?,                 th.kw,                     th.str,                 th.num,                 th.comment,
            chrome.diagnostic_error, chrome.diagnostic_warning, chrome.diagnostic_info, chrome.diagnostic_hint,
        };
        for (text_colors) |fg| try std.testing.expect(themeContrast(fg, th.bg.?) >= minimum);
        // Gutters are orientation aids, not source text: stay visible without
        // competing with comments or pulling attention away from the body.
        try std.testing.expect(themeContrast(th.lineno, th.bg.?) >= 2.5);
        try std.testing.expect(themeContrast(th.lineno, th.bg.?) <= 4);
        try std.testing.expect(themeContrast(th.lineno_active.?, th.bg.?) >= themeContrast(th.lineno, th.bg.?));
        try std.testing.expect(themeContrast(th.lineno_active.?, th.bg.?) <= 4.5);
        try std.testing.expect(themeContrast(th.comment, th.bg.?) >= 5);
        try std.testing.expect(themeContrast(th.comment, th.bg.?) >= themeContrast(th.lineno, th.bg.?) + 2);
        try std.testing.expect(themeContrast(th.tag_fg, th.tag_bg) >= minimum);
        try std.testing.expect(themeContrast(chrome.tag_active_fg, chrome.tag_active_bg) >= minimum);
        try std.testing.expect(th.tag_name_fg != null);
        try std.testing.expect(themeContrast(chrome.tag_name_fg, th.tag_bg) >= minimum);
        try std.testing.expect(themeContrast(chrome.tag_active_name_fg, chrome.tag_active_bg) >= minimum);
        // Focus stays on the same tonal surface, rather than inverting a
        // whole command strip. Text remains readable in both states.
        try std.testing.expect(themeContrast(chrome.tag_active_bg, th.tag_bg) <= 1.6);
        try std.testing.expect(themeContrast(chrome.tag_active_fg, th.tag_fg) <= 1.6);
        try std.testing.expect(themeContrast(th.sel_fg, th.sel_bg) >= minimum);
        try std.testing.expect(themeContrast(chrome.search_fg, chrome.search_bg) >= minimum);
        // ANSI black can intentionally match the page (for backgrounds). All
        // other ANSI foregrounds, including bright black, remain legible.
        for (th.palette.?[1..]) |fg| try std.testing.expect(themeContrast(fg, th.bg.?) >= minimum);
    }
}

test "native filename tints change hue without changing perceived lightness" {
    const Perceptual = struct {
        fn lab(rgb: [3]u8) [3]f64 {
            var linear: [3]f64 = undefined;
            for (rgb, 0..) |channel, i| {
                const value = @as(f64, @floatFromInt(channel)) / 255;
                linear[i] = if (value <= 0.04045) value / 12.92 else std.math.pow(f64, (value + 0.055) / 1.055, 2.4);
            }
            const r = linear[0];
            const g = linear[1];
            const b = linear[2];
            const l = std.math.cbrt(0.4122214708 * r + 0.5363325363 * g + 0.0514459929 * b);
            const m = std.math.cbrt(0.2119034982 * r + 0.6806995451 * g + 0.1073969566 * b);
            const n = std.math.cbrt(0.0883024619 * r + 0.2817188376 * g + 0.6299787005 * b);
            return .{
                0.2104542553 * l + 0.7936177850 * m - 0.0040720468 * n,
                1.9779984951 * l - 2.4285922050 * m + 0.4505937099 * n,
                0.0259040371 * l + 0.7827717662 * m - 0.8086757660 * n,
            };
        }
    };
    for (themes[0..native_theme_count]) |th| {
        try std.testing.expect(th.tag_name_fg != null and th.tag_active_name_fg != null);
        const chrome = ChromeTheme.fromTheme(&th);
        const pairs = [2][2][3]u8{
            .{ chrome.tag_fg, chrome.tag_name_fg },
            .{ chrome.tag_active_fg, chrome.tag_active_name_fg },
        };
        for (pairs) |pair| {
            const base = Perceptual.lab(pair[0]);
            const name = Perceptual.lab(pair[1]);
            // Half a lightness point allows 8-bit quantization without a
            // basename becoming visibly brighter or darker than its tag.
            try std.testing.expectApproxEqAbs(base[0], name[0], 0.005);
            const base_chroma = @sqrt(base[1] * base[1] + base[2] * base[2]);
            const name_chroma = @sqrt(name[1] * name[1] + name[2] * name[2]);
            try std.testing.expect(base_chroma > 0.005 and name_chroma > 0.02);
            // A normalized dot product <= cos(60 degrees) means a clear
            // hue difference, independent of saturation or lightness.
            const hue_cosine = (base[1] * name[1] + base[2] * name[2]) / (base_chroma * name_chroma);
            try std.testing.expect(hue_cosine <= 0.5);
        }
    }
}

test "native dark palettes choose near-black or deliberately soft contrast" {
    for (themes[0..native_theme_count]) |th| {
        if (themeContrast(th.bg.?, .{ 0, 0, 0 }) > 10) continue; // light paper
        const soft = std.mem.eql(u8, th.name, "dusk") or std.mem.eql(u8, th.name, "lagoon") or
            std.mem.eql(u8, th.name, "solarium") or std.mem.eql(u8, th.name, "forge_soft");
        if (soft) {
            try std.testing.expect(themeContrast(th.fg.?, th.bg.?) >= 4.5);
            try std.testing.expect(themeContrast(th.fg.?, th.bg.?) <= 7);
        } else {
            for (th.bg.?) |channel| try std.testing.expect(channel <= 0x14);
            try std.testing.expect(themeContrast(th.fg.?, th.bg.?) >= 14);
        }
    }
    const forge = curated.forge.theme;
    try std.testing.expectEqual(forge.bg[0], forge.bg[1]);
    // Forge chrome is cool-neutral, never the old green-over-blue mint cast.
    for ([_][3]u8{ forge.tag_bg, forge.tag_active_bg, forge.box, forge.border }) |rgb|
        try std.testing.expect(rgb[2] >= rgb[1]);
    try std.testing.expectEqual([3]u8{ 0, 0, 0 }, @as([3]u8, curated.forge_black.theme.bg));
    try std.testing.expectEqual([3]u8{ 0, 0, 0 }, @as([3]u8, curated.orchard_black.theme.bg));
}

test "line numbers stay quiet without a current-line tag background" {
    const gpa = std.testing.allocator;
    const p = try Pardes.init(gpa, .{ .tty_only = true, .cols = 80, .rows = 24 });
    defer p.deinit();
    const pane = try p.setTestFile("first\nsecond\n");
    pane.body.cur_pinned = true;
    pane.body.cur_row = 0;
    var custom = themes[0];
    custom.name = try gpa.dupe(u8, "quiet-gutter");
    custom.lineno = .{ 70, 70, 70 };
    custom.lineno_active = .{ 95, 95, 95 };
    p.custom_theme = custom;
    p.sync();
    const x = p.rects[0].x + config.GUTTER;
    const y = p.rects[0].y + BOX_H;
    for ([_]bool{ false, true }) |focus_tint| {
        p.settings.focus_tint = focus_tint;
        const surface = try p.render(p.scratch.allocator());
        try std.testing.expectEqual(Color{ .rgb = .{ 95, 95, 95 } }, surface.at(x, y).style.fg);
        try std.testing.expectEqual(Color{ .rgb = .{ 70, 70, 70 } }, surface.at(x, y + 1).style.fg);
        try std.testing.expectEqual(Color{ .rgb = custom.bg.? }, surface.at(x, y).style.bg);
        try std.testing.expect(surface.at(x, y).style.bold);
        try std.testing.expect(!surface.at(x, y + 1).style.bold);
    }
    // Old ThemeFile palettes need no new field, and do not regain the block.
    p.custom_theme.?.lineno_active = null;
    const fallback = try p.render(p.scratch.allocator());
    try std.testing.expectEqual(Color{ .rgb = .{ 70, 70, 70 } }, fallback.at(x, y).style.fg);
    try std.testing.expectEqual(Color{ .rgb = custom.bg.? }, fallback.at(x, y).style.bg);
    try std.testing.expect(fallback.at(x, y).style.bold);
    // Moving the caret clears the previous cue; editing the tag parks it.
    pane.body.cur_row = 1;
    const moved = try p.render(p.scratch.allocator());
    try std.testing.expect(!moved.at(x, y).style.bold);
    try std.testing.expect(moved.at(x, y + 1).style.bold);
    tagline.enterTag(p, pane);
    const tag_edit = try p.render(p.scratch.allocator());
    try std.testing.expect(!tag_edit.at(x, y + 1).style.bold);
}

test "legacy ThemeFile documents inherit Pardes UI roles without new fields" {
    @setEvalBranchQuota(10000);
    var encoded: std.Io.Writer.Allocating = .init(std.testing.allocator);
    defer encoded.deinit();
    try std.zon.stringify.serialize(curated.helix.theme, .{ .whitespace = true }, &encoded.writer);
    const source = try std.testing.allocator.dupeZ(u8, encoded.written());
    defer std.testing.allocator.free(source);
    const parsed = try std.zon.parse.fromSliceAlloc(Theme, std.testing.allocator, source, null, .{});
    defer std.zon.parse.free(std.testing.allocator, parsed);
    try std.testing.expectEqual(@as(?[3]u8, null), parsed.tag_active_bg);
    try std.testing.expectEqual(@as(?[3]u8, null), parsed.tag_name_fg);
    try std.testing.expectEqual(@as(?[3]u8, null), parsed.tag_active_name_fg);
    try std.testing.expectEqual(@as(?[3]u8, null), parsed.column_box);
    try std.testing.expectEqual(@as(?[3]u8, null), parsed.column_box_dim);
    try std.testing.expectEqual(@as(?[3]u8, null), parsed.search_bg);
    const chrome = ChromeTheme.fromTheme(&parsed);
    try std.testing.expectEqual(parsed.tag_bg, chrome.tag_active_bg);
    try std.testing.expectEqual(parsed.tag_fg, chrome.tag_name_fg);
    try std.testing.expectEqual(chrome.tag_active_fg, chrome.tag_active_name_fg);
    try std.testing.expectEqual(parsed.num, chrome.column_box);
    try std.testing.expectEqual(mix(parsed.num, parsed.tag_bg), chrome.column_box_dim);
    try std.testing.expectEqual(parsed.sel_bg, chrome.search_bg);
    try std.testing.expectEqual(parsed.fg.?, chrome.diagnostic_error);
}

test "column grip colors remain distinct from pane grips across native themes" {
    for (themes[0..native_theme_count]) |th| {
        try std.testing.expect(th.column_box != null and th.column_box_dim != null);
        const chrome = ChromeTheme.fromTheme(&th);
        for ([_][2][3]u8{
            .{ chrome.box, chrome.column_box },
            .{ chrome.box_dim, chrome.column_box_dim },
        }) |pair| {
            var distance: u32 = 0;
            for (pair[0], pair[1]) |a, b| {
                const delta = @as(i32, a) - b;
                distance += @intCast(delta * delta);
            }
            try std.testing.expect(distance >= 30 * 30);
        }
    }
    var custom = themes[0];
    custom.column_box = .{ 90, 130, 170 };
    custom.column_box_dim = null;
    var chrome = ChromeTheme.fromTheme(&custom);
    try std.testing.expectEqual(custom.column_box.?, chrome.column_box);
    try std.testing.expectEqual(mix(custom.column_box.?, custom.tag_bg), chrome.column_box_dim);
    custom.column_box_dim = .{ 40, 60, 80 };
    chrome = ChromeTheme.fromTheme(&custom);
    try std.testing.expectEqual(custom.column_box_dim.?, chrome.column_box_dim);
}

test "custom filename tints preserve optional active fallback precedence" {
    var theme = themes[0];
    theme.tag_name_fg = null;
    theme.tag_active_name_fg = null;
    var chrome = ChromeTheme.fromTheme(&theme);
    try std.testing.expectEqual(theme.tag_fg, chrome.tag_name_fg);
    try std.testing.expectEqual(theme.tag_active_fg.?, chrome.tag_active_name_fg);
    theme.tag_name_fg = .{ 120, 130, 140 };
    chrome = ChromeTheme.fromTheme(&theme);
    try std.testing.expectEqual(theme.tag_name_fg.?, chrome.tag_name_fg);
    try std.testing.expectEqual(theme.tag_name_fg.?, chrome.tag_active_name_fg);
    theme.tag_active_name_fg = .{ 150, 160, 170 };
    chrome = ChromeTheme.fromTheme(&theme);
    try std.testing.expectEqual(theme.tag_name_fg.?, chrome.tag_name_fg);
    try std.testing.expectEqual(theme.tag_active_name_fg.?, chrome.tag_active_name_fg);
    theme.tag_name_fg = null;
    chrome = ChromeTheme.fromTheme(&theme);
    try std.testing.expectEqual(theme.tag_fg, chrome.tag_name_fg);
    try std.testing.expectEqual(theme.tag_active_name_fg.?, chrome.tag_active_name_fg);
}