// MVK_CONFIG_USE_METAL_ARGUMENT_BUFFERS=1 -- use this if you're getting that odd crash on mac
b: *std.Build,
bEngine: *std.Build, // used to resolve executable paths from within the engine's root directory
opts: bh.Options,
nw_mod: *std.Build.Module,
gltf2ozz: ozz.GltfToOzz,
options: *std.Build.Step.Options,
cookShaders: bool,

backlogRoot: []const u8,

// list of all shaders discovered under
// content/_shaders/def
reflectShaderPathList: [][]u8 = undefined,

nwdep: *std.Build.Dependency,
// apigen: *std.Build.Step.Compile,
shaderEmbedGen: *std.Build.Step.Compile,
loadDynamicsGen: *std.Build.Step.Compile,
rcGen: *std.Build.Step.Compile,
specGen: *std.Build.Step.Compile,
generatedApis: std.StringHashMapUnmanaged(*std.Build.Module) = .{},

pub const BuildSystem = @This();
const std = @import("std");
const Build = std.Build;
const LazyPath = Build.LazyPath;

const ozz = @import("ozz");

pub const InitOptions = struct {
    import_name: []const u8 = "Backlog",
    backlogRoot: []const u8 = "./BacklogEngine",
    target: std.Build.ResolvedTarget,
    optimize: std.builtin.OptimizeMode,
};

pub fn init(b: *std.Build, initOptions: InitOptions) BuildSystem {
    const buildOpts = declareBuildOptions(b);

    var opts = bh.Options{
        .target = initOptions.target,
        .optimize = initOptions.optimize,
        .static_build = b.option(bool, "static_build", "builds backlog dependencies for static linking") orelse false,
        .tracy = b.option(bool, "tracy", "builds with tracy support") orelse false,
    };

    if (opts.target.result.os.tag == .linux) {
        // using a static build for linux... object loading hell is not fun...
        // i have skill issues in that realm right now
        std.debug.print("Important! only supporting static builds for linux", .{});
        opts.static_build = true;
    }

    const nwdep = b.dependency(initOptions.import_name, .{
        .target = opts.target,
        .optimize = opts.optimize,
        .static_build = opts.static_build,
    });

    var self = BuildSystem{
        .b = b,
        .bEngine = nwdep.builder,
        .opts = opts,
        .nw_mod = nwdep.module("Backlog"),
        .backlogRoot = initOptions.backlogRoot,
        .options = createGameOptions(b, buildOpts, opts),
        .gltf2ozz = ozz.GltfToOzz.init(nwdep.builder, .{}),
        .cookShaders = b.option(bool, "cookShaders", "generates shaders and updates .json files before running the build. (needs to be done whenever shaders are updated, this just runs tools/scripts/cook-shaders.py)") orelse false,

        .nwdep = nwdep,
        // .apigen = nwdep.artifact("backlog-apigen"),
        .loadDynamicsGen = nwdep.artifact("backlog-generate-loadDynamics"),
        .specGen = nwdep.artifact("backlog-generate-spec"),
        .rcGen = nwdep.artifact("backlog-generate-rc"),
        .shaderEmbedGen = nwdep.artifact("backlog-shaderEmbedGen"),
    };

    const exeList = [1]*std.Build.Step.Compile{self.gltf2ozz.exe};
    const install_tools = b.step("tools", "installs tools needed to generate outputs for the engine");
    for (exeList) |exe| {
        const toolsInstall = b.addInstallArtifact(exe, .{
            .dest_dir = .{ .override = .{ .custom = "tools" } },
        });

        install_tools.dependOn(&toolsInstall.step);
    }

    {
        const runArtifact = b.addRunArtifact(self.gltf2ozz.exe);
        if (b.args) |args| {
            runArtifact.addArgs(args);
        }

        const run_exe = b.step("gltf2ozz", "runs the gltf animation converter.");
        run_exe.dependOn(&runArtifact.step);
    }

    self.addDependencyInstalls(self.b, .ReleaseFast);

    return self;
}

// Build Options for the engine,
// should generally be written as false = default
// true = enabling something
const BuildOptions = struct {
    mutex_job_queue: bool,
    zero_logging: bool,
    slow_logging: bool,
    force_mailbox: bool,
};

fn declareBuildOptions(b: *std.Build) BuildOptions {
    return .{
        .mutex_job_queue = b.option(bool, "mutex_job_queue", "temporary test, reverts to old mutex based queue behaviour in jobs.zig:JobManager") orelse false,
        .zero_logging = b.option(bool, "zero_logging", "disables all logging, only intended for use on job dispatch testing") orelse false,
        .slow_logging = b.option(bool, "slow_logging", "Disables buffered logging, takes a hit to performance but gain timing information on logging") orelse false,
        .force_mailbox = b.option(bool, "force_mailbox", "forces mailbox mode for present mode. unlocks framerate to irresponsible levels") orelse false,
    };
}

fn createGameOptions(b: *std.Build, options: BuildOptions, bhopts: bh.Options) *std.Build.Step.Options {
    const opts = b.addOptions();

    inline for (@typeInfo(BuildOptions).@"struct".fields) |field| {
        opts.addOption(bool, field.name, @field(options, field.name));
    }

    // forward the options to the build options
    opts.addOption(bool, "tracy", bhopts.tracy);
    opts.addOption(bool, "static_build", bhopts.static_build);

    return opts;
}

pub fn addExtraModule(self: *BuildSystem, mod: *std.Build.Module, moduleName: []const u8) void {
    const dep = self.b.dependency(moduleName, .{ .target = self.opts.target, .optimize = self.opts.optimize, .static_build = self.opts.static_build });
    mod.addImport(moduleName, dep.module(moduleName));
}

fn addDependencyInstalls(self: *BuildSystem, b: *std.Build, optimize: std.builtin.OptimizeMode) void {
    if (self.opts.static_build) {
        return;
    }

    inline for (DynamicDepList) |d| {
        b.installArtifact(b.dependency(
            d.dep,
            .{ .target = self.opts.target, .optimize = optimize, .static_build = self.opts.static_build },
        ).artifact(d.artifact));
    }
}

const DynamicDepList: []const struct { dep: []const u8, artifact: []const u8 } = &.{
    .{ .dep = "sdl3", .artifact = "SDL3" },
    .{ .dep = "spng", .artifact = "spng_c" },
    .{ .dep = "lua", .artifact = "luac" },
    .{ .dep = "miniaudio", .artifact = "miniaudio_c" },
    .{ .dep = "zphysics", .artifact = "joltc" },
    // .{ .dep = "enet", .artifact = "enet_c" },
    .{ .dep = "ozz", .artifact = "ozz_cpp" },
};

// all other modules are disabled by default
pub const defaultEnabledModules: []const []const u8 = &.{
    "core",
    "assets",
    "platform",
    "rend",
};

pub const moduleOrder: []const []const u8 = &.{
    "core",
    "sys",
    "assets",
    "platform",
    "net",
    "physics",
    "audio",
    "rend",
    "ui",
    "imgui",
    "papyrus",
};

pub fn addProgram(
    self: *@This(),
    name: []const u8,
) *Program {
    const p = self.b.allocator.create(Program) catch unreachable;
    p.* = .{
        .name = name,
        .opts = self.opts,
        .buildSystem = self,
        .allocator = self.b.allocator,
    };

    return p;
}

pub fn generateRc(self: *@This(), programName: []const u8, iconPath: []const u8) !std.Build.LazyPath {
    const run = self.b.addRunArtifact(self.rcGen);
    const pfile = self.b.fmt("{s}.rc", .{programName});
    const output = run.addOutputFileArg(pfile);
    run.addArg(iconPath);

    return output;
}

pub fn generateInstallStaticResources(self: *@This(), programName: []const u8, shadersPath: []const u8) !*std.Build.Module {
    const run = self.b.addRunArtifact(self.shaderEmbedGen);
    const pfile = self.b.fmt("{s}ShaderGen.zig", .{programName});
    const output = run.addOutputFileArg(pfile);
    run.addArg(shadersPath);

    const b = self.b;
    const mod = self.b.addModule(pfile, .{
        .target = self.opts.target,
        .optimize = self.opts.optimize,
        .root_source_file = output,
    });
    mod.addImport("core", self.nwdep.module("core"));

    var dir = try std.fs.cwd().openDir("content/_shaders", .{ .iterate = true });
    defer dir.close();

    var walker = dir.iterate();
    while (try walker.next()) |shaderType| {
        if (shaderType.kind == .directory) {
            var d2 = try dir.openDir(shaderType.name, .{ .iterate = true });
            defer d2.close();
            var w2 = d2.iterate();
            while (try w2.next()) |shaderName| {
                const shaderPath = b.fmt("content/_shaders/{s}/{s}", .{ shaderType.name, shaderName.name });
                mod.addAnonymousImport(shaderName.name, .{
                    .root_source_file = b.path(shaderPath),
                });
            }
        }
    }

    return mod;
}

// ========= standalone build instance =======
// maybe the default should be like an engine launcher/project launcher or something
pub fn build(b: *std.Build) void {
    const opts = bh.declareOptions(b);
    engineDeps.buildGenerators(b, opts);
}

const bh = @import("bh");
const engineDeps = @import("build/engineDeps.zig");
const program = @import("build/program.zig");
const Program = program.Program;