const std = @import("std");
const build_config = @import("pardes_config");
const config = @import("config.zig");
const filesystem = @import("fs.zig");

const shader_dir = if (build_config.gui_shader_sources_prebuilt)
    "shaders/prebuilt/"
else
    "shaders/";
const ui_vertex_path = shader_dir ++ "ui.vert.glsl";
const ui_fragment_path = shader_dir ++ "ui.frag.glsl";
const image_vertex_path = shader_dir ++ "image.vert.glsl";
const image_fragment_path = shader_dir ++ "image.frag.glsl";
const post_vertex_path = shader_dir ++ "post.vert.glsl";
// The bundled post passes as compiled: the prefix and the pass together.
const post_crt_path = shader_dir ++ "post-crt.frag.glsl";
const post_ripple_path = shader_dir ++ "post-ripple.frag.glsl";
const post_glitch_path = shader_dir ++ "post-glitch.frag.glsl";

pub const Backend = @TypeOf(build_config.platform);
pub const backend: Backend = build_config.platform;

pub const GuiShaderSourceMode = enum {
    live,
    prebuilt_snapshot,

    pub fn label(mode: GuiShaderSourceMode) []const u8 {
        return switch (mode) {
            .live => "live GLSL compiled during this build",
            .prebuilt_snapshot => "paired GLSL snapshot for committed SPIR-V",
        };
    }
};

/// Only the SDL backend consumes GLSL/SPIR-V. Other backends deliberately have
/// no shader-source mode rather than being mislabeled "live" or "prebuilt".
pub fn guiShaderSourceMode() ?GuiShaderSourceMode {
    if (backend != .gui) return null;
    return if (build_config.gui_shader_sources_prebuilt)
        .prebuilt_snapshot
    else
        .live;
}

pub const files = switch (backend) {
    .tty => [_]filesystem.Source{
        .{ .path = "src/tty/panel_compositor.zig", .contents = @embedFile("tty/panel_compositor.zig") },
    },
    .gui => [_]filesystem.Source{
        .{ .path = "src/gui/gui.zig", .contents = @embedFile("gui/gui.zig") },
        .{ .path = "src/gui/Post.zig", .contents = @embedFile("gui/Post.zig") },
        .{ .path = ui_vertex_path, .contents = @embedFile("effect-source-ui.vert.glsl") },
        .{ .path = ui_fragment_path, .contents = @embedFile("effect-source-ui.frag.glsl") },
        .{ .path = image_vertex_path, .contents = @embedFile("effect-source-image.vert.glsl") },
        .{ .path = image_fragment_path, .contents = @embedFile("effect-source-image.frag.glsl") },
        .{ .path = post_vertex_path, .contents = @embedFile("effect-source-post.vert.glsl") },
        .{ .path = post_crt_path, .contents = @embedFile("effect-source-post-crt.frag.glsl") },
        .{ .path = post_ripple_path, .contents = @embedFile("effect-source-post-ripple.frag.glsl") },
        .{ .path = post_glitch_path, .contents = @embedFile("effect-source-post-glitch.frag.glsl") },
    },
    .macos => [_]filesystem.Source{
        .{ .path = "src/macos/Sources/PardesView.swift", .contents = @embedFile("macos/Sources/PardesView.swift") },
        .{ .path = "src/macos/Sources/ScenePostprocessor.swift", .contents = @embedFile("macos/Sources/ScenePostprocessor.swift") },
        .{ .path = "shaders/crt.ci.metal", .contents = @embedFile("effect-source-crt.ci.metal") },
    },
    .web, .esp32p4 => [_]filesystem.Source{},
};

pub fn forSetting(setting: config.Runtime.Setting) ?[]const []const u8 {
    return switch (setting.action) {
        .transition => switch (backend) {
            .tty => &.{ "src/layout.zig", "src/pardes.zig", "src/tty/panel_compositor.zig" },
            .gui => &.{ "src/layout.zig", "src/pardes.zig", "src/gui/gui.zig", ui_vertex_path, ui_fragment_path, image_vertex_path, image_fragment_path },
            .macos => &.{ "src/layout.zig", "src/pardes.zig", "src/macos/Sources/PardesView.swift", "src/macos/Sources/ScenePostprocessor.swift", "shaders/crt.ci.metal" },
            .web, .esp32p4 => null,
        },
        .scene => |effect| switch (backend) {
            .gui => switch (effect) {
                .crt => &.{ "src/gui/Post.zig", "src/gui/gui.zig", post_vertex_path, post_crt_path },
                .ripple => &.{ "src/gui/Post.zig", "src/gui/gui.zig", post_vertex_path, post_ripple_path },
                .glitch => &.{ "src/gui/Post.zig", "src/gui/gui.zig", post_vertex_path, post_glitch_path },
            },
            .macos => &.{ "src/macos/Sources/PardesView.swift", "src/macos/Sources/ScenePostprocessor.swift", "shaders/crt.ci.metal" },
            .tty, .web, .esp32p4 => null,
        },
        else => null,
    };
}

test "EffectCode paths resolve uniquely to this backend's archived inputs" {
    if (!@import("memory.zig").limits.embedded_sources) return error.SkipZigTest;
    for (config.Runtime.settings) |setting| {
        const available = switch (setting.action) {
            .transition => backend == .tty or backend == .gui or backend == .macos,
            .scene => backend == .gui or backend == .macos,
            else => false,
        };
        const paths = forSetting(setting);
        try std.testing.expectEqual(available, paths != null);
        if (paths) |listed| for (listed, 0..) |path, i| {
            const bytes = filesystem.sourceBytes(path) orelse return error.MissingEffectSource;
            try std.testing.expect(bytes.len > 0);
            for (listed[0..i]) |previous| try std.testing.expect(!std.mem.eql(u8, path, previous));
        };
    }
    for (files) |file| {
        const archived = filesystem.sourceBytes(file.path) orelse return error.MissingEffectSource;
        try std.testing.expectEqualStrings(file.contents, archived);
        var matches: usize = 0;
        for (filesystem.sources) |source| if (std.mem.eql(u8, source.path, file.path)) {
            matches += 1;
        };
        try std.testing.expectEqual(@as(usize, 1), matches);
    }
    try std.testing.expectEqual(backend == .tty, filesystem.sourceBytes("src/tty/panel_compositor.zig") != null);
    try std.testing.expectEqual(backend == .gui, filesystem.sourceBytes("src/gui/gui.zig") != null);
    try std.testing.expectEqual(backend == .macos, filesystem.sourceBytes("src/macos/Sources/PardesView.swift") != null);
}

test "shader source provenance is GUI-only and follows the build input" {
    if (comptime backend == .gui) {
        const expected: GuiShaderSourceMode = if (build_config.gui_shader_sources_prebuilt)
            .prebuilt_snapshot
        else
            .live;
        try std.testing.expectEqual(expected, guiShaderSourceMode().?);
        try std.testing.expect(expected.label().len > 0);
    } else try std.testing.expect(guiShaderSourceMode() == null);
}