const std = @import("std");

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

  const wasm = b.option(bool, "enable-wasm", "Enable Wasm support") orelse false;
  const shared = b.option(bool, "build-shared", "Build a shared library") orelse false;
  const amalgamated = b.option(bool, "amalgamated", "Build using an amalgamated source") orelse false;

  const lib: *std.Build.Step.Compile = if (!shared) b.addStaticLibrary(.{
    .name = "tree-sitter",
    .target = target,
    .optimize = optimize,
    .link_libc = true,
  }) else b.addSharedLibrary(.{
    .name = "tree-sitter",
    .pic = true,
    .target = target,
    .optimize = optimize,
    .link_libc = true,
  });

  if (amalgamated) {
    lib.addCSourceFile(.{
      .file = b.path("lib/src/lib.c"),
      .flags = &.{"-std=c11"},
    });
  } else {
    lib.addCSourceFiles(.{
      .root = b.path("lib/src"),
      .files = try findSourceFiles(b),
      .flags = &.{"-std=c11"},
    });
  }

  lib.addIncludePath(b.path("lib/include"));
  lib.addIncludePath(b.path("lib/src"));
  lib.addIncludePath(b.path("lib/src/wasm"));

  lib.root_module.addCMacro("_POSIX_C_SOURCE", "200112L");
  lib.root_module.addCMacro("_DEFAULT_SOURCE", "");

  if (wasm) {
    if (b.lazyDependency(wasmtimeDep(target.result), .{})) |wasmtime| {
      lib.root_module.addCMacro("TREE_SITTER_FEATURE_WASM", "");
      lib.addSystemIncludePath(wasmtime.path("include"));
      lib.addLibraryPath(wasmtime.path("lib"));
      lib.linkSystemLibrary("wasmtime");
    }
  }

  lib.installHeadersDirectory(b.path("lib/include"), ".", .{});

  b.installArtifact(lib);
}

fn wasmtimeDep(target: std.Target) []const u8 {
  const arch = target.cpu.arch;
  const os = target.os.tag;
  const abi = target.abi;
  return switch (os) {
    .linux => switch (arch) {
      .x86_64 => switch (abi) {
        .gnu => "wasmtime_c_api_x86_64_linux",
        .musl => "wasmtime_c_api_x86_64_musl",
        .android => "wasmtime_c_api_x86_64_android",
        else => null
      },
      .aarch64 => switch (abi) {
        .gnu => "wasmtime_c_api_aarch64_linux",
        .android => "wasmtime_c_api_aarch64_android",
        else => null
      },
      .s390x => "wasmtime_c_api_s390x_linux",
      .riscv64 => "wasmtime_c_api_riscv64gc_linux",
      else => null
    },
    .windows => switch (arch) {
      .x86_64 => switch (abi) {
        .gnu => "wasmtime_c_api_x86_64_mingw",
        .msvc => "wasmtime_c_api_x86_64_windows",
        else => null
      },
      else => null
    },
    .macos => switch (arch) {
      .x86_64 => "wasmtime_c_api_x86_64_macos",
      .aarch64 => "wasmtime_c_api_aarch64_macos",
      else => null
    },
    else => null
  } orelse std.debug.panic(
    "Unsupported target for wasmtime: {s}-{s}-{s}",
    .{ @tagName(arch), @tagName(os), @tagName(abi) }
  );
}

fn findSourceFiles(b: *std.Build) ![]const []const u8 {
  var sources = std.ArrayList([]const u8).init(b.allocator);

  var dir = try b.build_root.handle.openDir("lib/src", .{ .iterate = true });
  var iter = dir.iterate();
  defer dir.close();

  while (try iter.next()) |entry| {
    if (entry.kind != .file) continue;
    const file = entry.name;
    const ext = std.fs.path.extension(file);
    if (std.mem.eql(u8, ext, ".c") and !std.mem.eql(u8, file, "lib.c")) {
      try sources.append(b.dupe(file));
    }
  }

  return sources.items;
}