// SPDX-License-Identifier: LCL-1.0
// Copyright (c) 2026 Markus Maiwald
// Stewardship: Self Sovereign Society Foundation
//
// This file is part of the Nexus Commonwealth.
// See legal/LICENSE_COMMONWEALTH.md for license terms.

//! Rumpk Build System
//!
//! Orchestrates L0 (Zig) and L1 (Nim) compilation.
//! Builds the Hardware Abstraction Layer as a static library.

const std = @import("std");

pub fn build(b: *std.Build) void {
    const target = b.standardTargetOptions(.{});
    const optimize = b.standardOptimizeOption(.{});

    // =========================================================
    // L0: Hardware Abstraction Layer (Zig)
    // =========================================================

    // NOTE(Build): Zig 0.15.x API - using addLibrary with static linkage
    const hal_mod = b.createModule(.{
        .root_source_file = b.path("hal/abi.zig"),
        .target = target,
        .optimize = optimize,
    });
    // Freestanding kernel - no libc, no red zone, no stack checks
    hal_mod.red_zone = false;
    hal_mod.stack_check = false;
    hal_mod.code_model = .medany;

    const hal = b.addLibrary(.{
        .name = "rumpk_hal",
        .root_module = hal_mod,
        .linkage = .static,
    });

    b.installArtifact(hal);

    // TODO(Build): Microui needs stdio.h stubs for freestanding.
    // Re-enable after creating libs/microui/stdio_stub.h
    // Microui Integration (Phase 3.5b)
    // hal_mod.addIncludePath(b.path("libs/microui"));
    // hal_mod.addCSourceFile(.{
    //     .file = b.path("libs/microui/microui.c"),
    //     .flags = &.{"-std=c99"},
    // });

    // =========================================================
    // Boot: Entry Point (Assembly + Zig)
    // =========================================================

    const boot_mod = b.createModule(.{
        .root_source_file = b.path("boot/header.zig"),
        .target = target,
        .optimize = optimize,
    });
    boot_mod.red_zone = false;
    boot_mod.stack_check = false;
    boot_mod.code_model = .medany;

    const boot = b.addObject(.{
        .name = "boot",
        .root_module = boot_mod,
    });

    // =========================================================
    // Final Link: rumpk.elf
    // =========================================================

    const kernel_mod = b.createModule(.{
        .root_source_file = b.path("hal/abi.zig"), // Fake root, we add objects later
        .target = target,
        .optimize = optimize,
    });
    kernel_mod.red_zone = false;
    kernel_mod.stack_check = false;
    kernel_mod.code_model = .medany;

    const kernel = b.addExecutable(.{
        .name = "rumpk.elf",
        .root_module = kernel_mod,
    });

    kernel.setLinkerScript(b.path("boot/linker.ld"));
    kernel.addObject(boot);
    // kernel.linkLibrary(hal); // Redundant, already in kernel_mod

    // Add Nim-generated objects
    {
        var nimcache_dir = std.fs.cwd().openDir("build/nimcache", .{ .iterate = true }) catch |err| {
            std.debug.print("Warning: Could not open nimcache dir: {}\n", .{err});
            return;
        };
        defer nimcache_dir.close();
        var it = nimcache_dir.iterate();
        while (it.next() catch null) |entry| {
            if (entry.kind == .file and std.mem.endsWith(u8, entry.name, ".o")) {
                const path = b.fmt("build/nimcache/{s}", .{entry.name});
                kernel.addObjectFile(b.path(path));
            }
        }
    }

    // Add external pre-built dependencies (Order matters: Libs after users)
    kernel.addObjectFile(b.path("build/switch.o")); // cpu_switch_to
    kernel.addObjectFile(b.path("build/sys_arch.o")); // sys_now, nexus_lwip_panic
    kernel.addObjectFile(b.path("build/libc_shim.o"));
    kernel.addObjectFile(b.path("build/clib.o"));
    kernel.addObjectFile(b.path("build/liblwip.a"));
    kernel.addObjectFile(b.path("build/initrd.o"));

    b.installArtifact(kernel);

    // =========================================================
    // Tests
    // =========================================================

    const test_mod = b.createModule(.{
        .root_source_file = b.path("hal/abi.zig"),
        .target = target,
        .optimize = optimize,
    });

    const hal_tests = b.addTest(.{
        .root_module = test_mod,
    });

    const run_tests = b.addRunArtifact(hal_tests);
    const test_step = b.step("test", "Run Rumpk HAL tests");
    test_step.dependOn(&run_tests.step);
}