#!/usr/bin/env node
import { execFile } from "node:child_process";
import { createHash } from "node:crypto";
import { availableParallelism } from "node:os";
import {
  copyFile, mkdir, readFile, readdir, rm, stat, writeFile,
} from "node:fs/promises";
import { basename, dirname, join, relative, sep } from "node:path";
import { fileURLToPath } from "node:url";
import { promisify } from "node:util";
import { RUNTIME_PACK_MATRIX } from "../runtime-pack-matrix.mjs";
import { createDeterministicArchive } from "./archive.mjs";
import { installRuntimePack, withBuildLock } from "./build-state.mjs";

const run = promisify(execFile);
const packageRoot = dirname(dirname(fileURLToPath(import.meta.url)));
const repoRoot = fileURLToPath(new URL("../../..", import.meta.url));
const runtimeRoot = join(repoRoot, "packages/runtime");
const runtimeSrc = join(runtimeRoot, "src");
const vendorRoot = join(runtimeRoot, "vendor");
const outputRoot = join(packageRoot, "artifacts");
const manifestPath = join(packageRoot, "runtime-pack.json");

if (process.platform !== "darwin" || process.arch !== "arm64") {
  process.stdout.write("@scriptc/runtime-darwin-arm64: skipped on this host\n");
  process.exit(0);
}

async function build() {
  const buildRoot = join(
    packageRoot,
    `.runtime-pack-build-${process.pid}-${Math.random().toString(36).slice(2)}`,
  );
  const stagedOutputRoot = join(buildRoot, "artifacts");
  const stagedManifestPath = join(buildRoot, "runtime-pack.json");
  const artifactPath = (path) =>
    ["artifacts", ...relative(stagedOutputRoot, path).split(sep)].join("/");
  const sourcePathFlags = [
    `-ffile-prefix-map=${buildRoot}=${packageRoot}`,
    `-ffile-prefix-map=${repoRoot}=.`,
  ];

  const packageManifest = JSON.parse(await readFile(join(packageRoot, "package.json"), "utf8"));
  const compiler = process.env.CC ?? "clang";
  const archiver = process.env.AR ?? "ar";
  const compilerVersion = (await run(compiler, ["--version"])).stdout.split("\n", 1)[0].trim();
  const commonFlags = [
    "-target", RUNTIME_PACK_MATRIX.target.llvm_triple,
    "-std=c11", "-pthread", "-fno-math-errno", "-fno-strict-aliasing",
    ...RUNTIME_PACK_MATRIX.executable_section_elimination.compile_flags,
    "-Wno-deprecated-declarations", "-I", runtimeSrc,
  ];
  const quickjs = join(vendorRoot, "quickjs-ng");
  const zlib = join(vendorRoot, "zlib");
  const mbedtls = join(vendorRoot, "mbedtls");
  const QJS_SOURCES = ["dtoa.c", "libregexp.c", "libunicode.c", "quickjs.c"];
  const LRE_SOURCES = ["libregexp.c", "libunicode.c"];
  const ZLIB_SOURCES = [
    "adler32.c", "compress.c", "crc32.c", "deflate.c", "infback.c",
    "inffast.c", "inflate.c", "inftrees.c", "trees.c", "uncompr.c", "zutil.c",
  ];

  async function sha256(path) {
    return createHash("sha256").update(await readFile(path)).digest("hex");
  }

  async function compile(source, output, flags) {
    await mkdir(dirname(output), { recursive: true });
    await run(compiler, [...sourcePathFlags, ...flags, "-c", source, "-o", output]);
  }

  async function parallel(items, task) {
    const width = Math.max(1, Math.min(8, availableParallelism()));
    for (let i = 0; i < items.length; i += width) {
      await Promise.all(items.slice(i, i + width).map(task));
    }
  }

  async function archive(id, sources, sourceRoot, flags) {
    const root = join(stagedOutputRoot, "vendor", id);
    const objectRoot = join(root, "objects");
    await parallel(sources, async (source) => {
      await compile(join(sourceRoot, source), join(objectRoot, source.replace(/\.c$/, ".o")), flags);
    });
    const output = join(root, `libscriptc-${id}.a`);
    const objects = sources.map((source) => join(objectRoot, source.replace(/\.c$/, ".o")));
    await createDeterministicArchive(archiver, output, objects);
    await rm(objectRoot, { recursive: true, force: true });
    return {
      id,
      path: artifactPath(output),
      sha256: await sha256(output),
      size: (await stat(output)).size,
    };
  }

  await rm(buildRoot, { recursive: true, force: true });
  await mkdir(stagedOutputRoot, { recursive: true });

  try {
    const flavors = {};
    for (const [flavor, flavorSpec] of Object.entries(RUNTIME_PACK_MATRIX.flavors)) {
      const units = [];
      for (const unit of RUNTIME_PACK_MATRIX.runtime_units) {
        const variants = [];
        for (const variant of unit.variants) {
          const variantName = variant.id === "default" ? "default" : variant.id;
          const output = join(
            stagedOutputRoot,
            flavor,
            "runtime",
            variantName,
            unit.source.replace(/\.c$/, ".o"),
          );
          const includeFlags = [
            ...(unit.source === "scr_regex.c" || variant.defines.includes("SCR_DYNAMIC")
              ? ["-I", quickjs]
              : []),
            ...(unit.source === "scr_tls.c" ? ["-I", join(mbedtls, "include")] : []),
            ...(unit.source === "scr_zlib.c" || unit.source === "scr_fetch.c"
              ? ["-I", zlib]
              : []),
          ];
          await compile(join(runtimeSrc, unit.source), output, [
            ...commonFlags, flavorSpec.optimization,
            ...variant.defines.map((define) => `-D${define}`),
            ...includeFlags,
          ]);
          variants.push({
            id: variant.id,
            when: variant.when,
            defines: variant.defines,
            path: artifactPath(output),
            sha256: await sha256(output),
            size: (await stat(output)).size,
          });
        }
        units.push({ source: unit.source, predicate: unit.predicate, variants });
      }
      flavors[flavor] = { optimization: flavorSpec.optimization, runtime_units: units };
    }

    const mbedtlsSources = (await readdir(join(mbedtls, "library")))
      .filter((name) => !name.startsWith(".") && name.endsWith(".c"))
      .sort();
    const archives = [
      await archive("quickjs", QJS_SOURCES, quickjs, [
        "-target", RUNTIME_PACK_MATRIX.target.llvm_triple, "-std=gnu11",
        "-fvisibility=hidden", "-funsigned-char", "-DQUICKJS_NG_BUILD",
        "-D_GNU_SOURCE", "-DNDEBUG", "-Os", "-I", quickjs,
      ]),
      await archive("libregexp", LRE_SOURCES, quickjs, [
        "-target", RUNTIME_PACK_MATRIX.target.llvm_triple, "-std=c11", "-Os", "-I", quickjs,
      ]),
      await archive("zlib", ZLIB_SOURCES, zlib, [
        "-target", RUNTIME_PACK_MATRIX.target.llvm_triple, "-std=c11", "-Os", "-I", zlib,
      ]),
      await archive("mbedtls", mbedtlsSources, join(mbedtls, "library"), [
        "-target", RUNTIME_PACK_MATRIX.target.llvm_triple, "-std=c11", "-Os",
        "-I", join(mbedtls, "include"), "-I", join(mbedtls, "library"),
      ]),
    ];
    const archiveSpecs = new Map(RUNTIME_PACK_MATRIX.archives.map((entry) => [entry.id, entry]));
    const licensed = [
      [join(runtimeRoot, "LICENSE"), "artifacts/licenses/scriptc-runtime.txt", "Apache-2.0"],
      [join(quickjs, "LICENSE"), "artifacts/licenses/quickjs-ng.txt", "MIT"],
      [join(vendorRoot, "ryu", "LICENSE-Boost"), "artifacts/licenses/ryu.txt", "BSL-1.0"],
      [join(zlib, "LICENSE"), "artifacts/licenses/zlib.txt", "Zlib"],
      [join(mbedtls, "LICENSE"), "artifacts/licenses/mbedtls.txt", "Apache-2.0"],
    ];
    await Promise.all(licensed.map(async ([source, destination]) => {
      const output = join(buildRoot, destination);
      await mkdir(dirname(output), { recursive: true });
      await copyFile(source, output);
    }));
    const manifest = {
      schema: "scriptc.runtime-pack.v1",
      format: 1,
      package: packageManifest.name,
      version: packageManifest.version,
      target: RUNTIME_PACK_MATRIX.target,
      runtime_abi: { version: 1, marker: "scr_runtime_abi_v1" },
      compiler: {
        command: compiler,
        identity: compilerVersion,
        target: RUNTIME_PACK_MATRIX.target.llvm_triple,
      },
      macros: {
        executable: ["SCR_DYNAMIC", "SCR_TEXT_DECODER_LEGACY"],
        excluded: ["SCR_LIB", "SCR_THREAD_INSTANCES", "SCR_RC_AUDIT", "SCR_ASAN_FIBERS"],
        sanitizer: "external-toolchain-required",
      },
      flavors,
      archives: archives.map((entry) => ({ ...entry, predicate: archiveSpecs.get(entry.id).predicate })),
      system_libraries: RUNTIME_PACK_MATRIX.system_libraries,
      licenses: licensed.map(([, path, license]) => ({ path, license })),
    };
    await writeFile(stagedManifestPath, `${JSON.stringify(manifest, null, 2)}\n`);
    const backupSuffix = `${process.pid}-${Math.random().toString(36).slice(2)}`;
    await installRuntimePack({
      outputRoot,
      manifestPath,
      stagedOutputRoot,
      stagedManifestPath,
      backupRoot: join(packageRoot, `.runtime-pack-artifacts-backup-${backupSuffix}`),
      backupManifestPath: join(packageRoot, `.runtime-pack-manifest-backup-${backupSuffix}`),
    });
    process.stdout.write(
      `built ${packageManifest.name}@${packageManifest.version}: ` +
      `${Object.keys(flavors).length} flavors, ${archives.length} vendor archives\n`,
    );
  } finally {
    await rm(buildRoot, { recursive: true, force: true });
  }
}

await withBuildLock(join(packageRoot, ".runtime-pack-build.lock"), build);