import { readdir, readFile, writeFile } from "fs/promises";
import { join } from "path";

const outdir = "dist";

// Step 1: Clean output directory
const { rmSync } = await import("fs");
rmSync(outdir, { recursive: true, force: true });

// Step 2: Bundle with splitting
const result = await Bun.build({
    entrypoints: ["src/entrypoints/cli.tsx"],
    outdir,
    target: "bun",
    splitting: true,
});

if (!result.success) {
    console.error("Build failed:");
    for (const log of result.logs) {
        console.error(log);
    }
    process.exit(1);
}

// Step 3: Post-process — patch for Node.js compatibility & re-enable feature-flagged code
const files = await readdir(outdir);

// 3a. Replace import.meta.require with Node.js compat shim
const IMPORT_META_REQUIRE = "var __require = import.meta.require;";
const COMPAT_REQUIRE = `var __require = typeof import.meta.require === "function" ? import.meta.require : (await import("module")).createRequire(import.meta.url);`;

// 3b. Re-enable feature-flagged code that was DCE'd (dead-code-eliminated) by the bundler.
// The Bun bundler resolves `feature('BUDDY')` from bun:bundle to `false` at build time,
// turning `if (!feature('BUDDY')) return X` into `if (true) return X` (dead code).
// We need to remove these guards to re-enable the buddy system.
// Pattern: `if (true)\n    return 0;`  → remove (companionReservedColumns guard)
// Pattern: `if (true)\n    return null;` → remove (CompanionSprite render guard)
// Pattern: `if (true)\n    return [];`  → remove (findBuddyTriggerPositions guard)
// Pattern: `if (true) {\n    return;\n  }` → remove (useEffect guard)
//
// We specifically target buddy-related functions by checking surrounding context.

const BUDDY_FUNCTIONS = [
    'companionReservedColumns',
    'CompanionSprite',
    'CompanionFloatingBubble',
    'findBuddyTriggerPositions',
];

let patched = 0;
let buddyPatched = 0;
for (const file of files) {
    if (!file.endsWith(".js")) continue;
    const filePath = join(outdir, file);
    let content = await readFile(filePath, "utf-8");
    let changed = false;

    // Patch import.meta.require
    if (content.includes(IMPORT_META_REQUIRE)) {
        content = content.replace(IMPORT_META_REQUIRE, COMPAT_REQUIRE);
        patched++;
        changed = true;
    }

    // Re-enable buddy feature flags: remove DCE'd guards
    // These patterns are generated by the bundler when it resolves feature('BUDDY') to false
    // and negates it: !false → true, creating `if (true) return X;` dead code guards.
    if (content.includes('CompanionSprite') || content.includes('companionReservedColumns') ||
        content.includes('findBuddyTriggerPositions') || content.includes('useBuddyNotification')) {

        // Pattern 1: `if (true)\n    return 0;` (single-line early return)
        content = content.replace(/if \(true\)\n\s*return 0;/g, '/* buddy-enabled */');
        // Pattern 2: `if (true)\n    return null;` (component early return)
        content = content.replace(/if \(true\)\n\s*return null;/g, '/* buddy-enabled */');
        // Pattern 3: `if (true)\n    return \[\];` (array early return)
        content = content.replace(/if \(true\)\n\s*return \[\];/g, '/* buddy-enabled */');
        // Pattern 4: `if (true) {\n    return;\n  }` (void early return)
        content = content.replace(/if \(true\) \{\n\s*return;\n\s*\}/g, '/* buddy-enabled */');
        // Pattern 5: `if (true) {\n    return null;\n  }` (block return null)
        content = content.replace(/if \(true\) \{\n\s*return null;\n\s*\}/g, '/* buddy-enabled */');
        // Pattern 6: `if (true) {\n    return false;\n  }` (block return false)
        content = content.replace(/if \(true\) \{\n\s*return false;\n\s*\}/g, '/* buddy-enabled */');

        buddyPatched++;
        changed = true;
    }

    // Also fix REPL.tsx buddy rendering conditions
    // The bundler turns `feature('BUDDY') && expr` into `false && expr` → `false`
    // and `!feature('BUDDY')` into `true`
    // In REPL, the inline expressions like:
    //   `feature('BUDDY') && companionVisible && ...` become just `false`
    // We need to restore these. The pattern in the compiled REPL is typically:
    //   `bottomFloat={false}` (was `bottomFloat={feature('BUDDY') && ...}`)
    //   `false && companionNarrow` (was `feature('BUDDY') && companionNarrow`)
    // These are harder to fix generically. Let's handle the PromptInput/REPL chunk.
    if (content.includes('companionVisible') && content.includes('companionNarrow')) {
        // The REPL renders companion in two places:
        // 1. Fullscreen: bottomFloat={feature('BUDDY') && companionVisible && !companionNarrow ? <CompanionFloatingBubble /> : undefined}
        //    Compiled to: bottomFloat={false ? ... : undefined} → bottomFloat={undefined}
        // 2. Non-fullscreen: {feature('BUDDY') && !(companionNarrow && isFullscreenEnvEnabled()) && companionVisible ? <CompanionSprite /> : null}
        //    Compiled to: {false ? ... : null} → null

        // Replace `false && companionNarrow` patterns (used in flex direction)
        content = content.replace(
            /false && companionNarrow/g,
            'companionNarrow'
        );

        // Fix companion sprite rendering: find places where `null` replaced the companion
        // Look for the pattern near companionVisible: `null` where `<CompanionSprite />` should be
        // This is trickier. Let's look for specific compiled patterns.

        changed = true;
    }

    if (changed) {
        await writeFile(filePath, content);
    }
}

// Step 4: Replace shebang from bun to node for npm compatibility
const cliPath = join(outdir, "cli.js");
let cliContent = await readFile(cliPath, "utf-8");

// 4a. Replace shebang
if (cliContent.startsWith("#!/usr/bin/env bun")) {
    cliContent = cliContent.replace("#!/usr/bin/env bun", "#!/usr/bin/env node");
}

// 4b. Inject Node.js compatibility shim
const COMPAT_SHIM = `
// ── Node.js compatibility shim ──
if (typeof globalThis.Bun === "undefined") {
  // Ensure typeof Bun checks return "undefined" (not ReferenceError)
}
`;

const firstNewline = cliContent.indexOf("\n");
if (firstNewline !== -1) {
    cliContent = cliContent.slice(0, firstNewline + 1) + COMPAT_SHIM + cliContent.slice(firstNewline + 1);
}

await writeFile(cliPath, cliContent);

console.log(`Bundled ${result.outputs.length} files to ${outdir}/ (patched ${patched} require, ${buddyPatched} buddy chunks, shebang → node)`);