/**
 * Bake git commit and build channel into meshchatx/src/_build_meta_baked.py
 * (gitignored). meshchatx.src.build_meta imports that overlay when present.
 *
 * Invoked from scripts/sync_version.js (pnpm run version:sync / build).
 *
 * Channel detection (first match wins):
 *   MESHCHATX_BUILD_CHANNEL env
 *   GITHUB_REF_NAME / GITHUB_REF (nightly-*, preview-dev-*, preview-*, vX.Y.Z)
 *   default: local (is_dev)
 *
 * Dev channels (nightly, preview-dev, preview, local) set IS_DEV_BUILD.
 * Release tags (vX.Y.Z) clear IS_DEV_BUILD.
 */

const fs = require("fs");
const path = require("path");
const { execFileSync } = require("child_process");

const root = path.resolve(__dirname, "..");
const metaPath = path.join(root, "meshchatx", "src", "_build_meta_baked.py");

function envTrim(name) {
    const v = process.env[name];
    return typeof v === "string" ? v.trim() : "";
}

function git(args) {
    try {
        return execFileSync("git", args, {
            cwd: root,
            encoding: "utf8",
            stdio: ["ignore", "pipe", "ignore"],
        }).trim();
    } catch {
        return "";
    }
}

function resolveCommit() {
    const fromEnv = envTrim("MESHCHATX_GIT_COMMIT") || envTrim("GIT_COMMIT") || envTrim("GITHUB_SHA");
    if (fromEnv) {
        return fromEnv;
    }
    return git(["rev-parse", "HEAD"]);
}

function shortCommit(full) {
    if (!full) {
        return "";
    }
    if (/^[0-9a-f]{7,40}$/i.test(full)) {
        return full.slice(0, 7).toLowerCase();
    }
    const fromGit = git(["rev-parse", "--short=7", "HEAD"]);
    return fromGit || full.slice(0, 7);
}

function refName() {
    return (
        envTrim("MESHCHATX_BUILD_REF") ||
        envTrim("GITHUB_REF_NAME") ||
        envTrim("GITHUB_REF").replace(/^refs\/(heads|tags)\//, "")
    );
}

function resolveChannel(ref) {
    const forced = envTrim("MESHCHATX_BUILD_CHANNEL").toLowerCase();
    if (forced) {
        return forced;
    }
    if (!ref) {
        return "local";
    }
    if (ref.startsWith("nightly-")) {
        return "nightly";
    }
    if (ref.startsWith("preview-dev-")) {
        return "preview-dev";
    }
    if (ref.startsWith("preview-")) {
        return "preview";
    }
    if (/^v\d+\.\d+\.\d+/.test(ref)) {
        return "release";
    }
    return "local";
}

function isDevChannel(channel) {
    return channel !== "release";
}

function pyString(value) {
    return JSON.stringify(String(value ?? ""));
}

function bake() {
    const commit = resolveCommit();
    const short = shortCommit(commit);
    const ref = refName();
    const channel = resolveChannel(ref);
    const isDev = isDevChannel(channel);

    const content = `# SPDX-License-Identifier: 0BSD
"""Generated by scripts/bake_build_meta.js. Do not commit."""

GIT_COMMIT = ${pyString(commit)}
GIT_COMMIT_SHORT = ${pyString(short)}
BUILD_CHANNEL = ${pyString(channel)}
IS_DEV_BUILD = ${isDev ? "True" : "False"}
`;

    const prev = fs.existsSync(metaPath) ? fs.readFileSync(metaPath, "utf8") : null;
    if (prev !== content) {
        fs.writeFileSync(metaPath, content, "utf8");
        console.log(`Baked build_meta channel=${channel} is_dev=${isDev} commit=${short || "unknown"}`);
    } else {
        console.log(`build_meta unchanged channel=${channel} is_dev=${isDev} commit=${short || "unknown"}`);
    }
}

bake();