#!/usr/bin/env node
/**
 * Reprocess uploads for existing Photo documents.
 *
 * - For each Photo in Mongo, find a matching source image in uploads/.
 * - Apply the same watermark + resize pipeline used by the upload endpoint.
 * - Write main/medium/thumb variants (WEBP) and update the Photo doc paths.
 * - Photos without a matching source file are skipped.
 *
 * Usage:
 *   APPLY=1 node scripts/reprocess_uploads.js   # actually write files + update docs
 *   node scripts/reprocess_uploads.js           # dry run (default)
 *
 * Env:
 *   MONGO_URI (optional) - defaults to mongodb://localhost:27017/photogallery
 */

const fs = require('fs');
const fsPromises = fs.promises;
const path = require('path');
const crypto = require('crypto');
const sharp = require('sharp');
const mongoose = require('mongoose');
const Photo = require('../models/photo');

const MONGO_URI = process.env.MONGO_URI || 'mongodb://localhost:27017/photogallery';
const APPLY = process.env.APPLY === '1';
const UPLOAD_DIR = path.join(__dirname, '..', 'uploads');

const VARIANTS = {
    main: { size: 2000, quality: 82, suffix: '' },
    medium: { size: 1200, quality: 80, suffix: '-md' },
    thumb: { size: 640, quality: 76, suffix: '-sm' },
};

const diagonalOverlay = Buffer.from(`
    <svg width="2400" height="2400" viewBox="0 0 2400 2400" xmlns="http://www.w3.org/2000/svg">
        <defs>
            <linearGradient id="diagGrad" x1="0%" y1="0%" x2="100%" y2="100%">
                <stop offset="0%" stop-color="rgba(255,255,255,0.22)" />
                <stop offset="50%" stop-color="rgba(255,255,255,0.33)" />
                <stop offset="100%" stop-color="rgba(255,255,255,0.22)" />
            </linearGradient>
        </defs>
        <g transform="translate(1200 1200) rotate(-32)">
            <text x="0" y="-80" text-anchor="middle" dominant-baseline="middle"
                fill="url(#diagGrad)" stroke="rgba(0,0,0,0.16)" stroke-width="8"
                font-family="Arial Black, Arial, sans-serif" font-size="260" letter-spacing="6" textLength="1800" lengthAdjust="spacingAndGlyphs">
                BEACH PARTY
                <tspan x="0" dy="280">BALLOONS</tspan>
            </text>
        </g>
    </svg>
`);

const HEIF_BRANDS = new Set(['heic', 'heix', 'hevc', 'heim', 'heis', 'hevm', 'hevs', 'mif1', 'msf1', 'avif', 'avis']);
const isHeifBuffer = (buffer) => buffer && buffer.length >= 12 && HEIF_BRANDS.has(buffer.slice(8, 12).toString('ascii').toLowerCase());

function parseBaseName(doc) {
    const raw = path.basename(doc.filename || doc.path || '', path.extname(doc.filename || doc.path || ''));
    const match = raw.match(/^(.*?)(-md|-sm)?$/);
    return match ? match[1] : raw;
}

function sourceCandidates(doc) {
    const baseName = parseBaseName(doc);
    const preferred = [];
    const fromDocPath = doc.path ? doc.path.replace(/^\/+/, '') : '';
    const fromDocFile = doc.filename ? path.join('uploads', doc.filename) : '';
    [fromDocPath, fromDocFile]
        .filter(Boolean)
        .forEach(rel => preferred.push(path.join(UPLOAD_DIR, rel.replace(/^uploads[\\/]/, ''))));

    preferred.push(
        path.join(UPLOAD_DIR, `${baseName}.webp`),
        path.join(UPLOAD_DIR, `${baseName}-md.webp`),
        path.join(UPLOAD_DIR, `${baseName}-sm.webp`)
    );
    return preferred;
}

async function findExistingFile(candidates) {
    for (const file of candidates) {
        try {
            const stat = await fsPromises.stat(file);
            if (stat.isFile()) return file;
        } catch (_) { /* ignore missing */ }
    }
    return null;
}

async function stampAndVariants(inputBuffer, baseName) {
    // Build main stamped image
    const base = sharp(inputBuffer)
        .rotate()
        .resize({ width: VARIANTS.main.size, height: VARIANTS.main.size, fit: 'inside', withoutEnlargement: true })
        .toColorspace('srgb');

    const { data: baseBuffer, info } = await base.toBuffer({ resolveWithObject: true });
    const targetWidth = Math.max(Math.floor((info.width || VARIANTS.main.size) * 0.98), 1);
    const targetHeight = Math.max(Math.floor((info.height || VARIANTS.main.size) * 0.98), 1);

    const overlayBuffer = await sharp(diagonalOverlay, { density: 300 })
        .resize({ width: targetWidth, height: targetHeight, fit: 'cover' })
        .png()
        .toBuffer();

    const stamped = await sharp(baseBuffer)
        .composite([{ input: overlayBuffer, gravity: 'center' }])
        .toFormat('webp', { quality: VARIANTS.main.quality, effort: 5 })
        .toBuffer();

    const outputs = {
        main: { filename: `${baseName}${VARIANTS.main.suffix}.webp`, buffer: stamped },
    };

    const createVariant = async (key, opts) => {
        const resized = await sharp(stamped)
            .resize({ width: opts.size, height: opts.size, fit: 'inside', withoutEnlargement: true })
            .toFormat('webp', { quality: opts.quality, effort: 5 })
            .toBuffer();
        outputs[key] = { filename: `${baseName}${opts.suffix}.webp`, buffer: resized };
    };
    await createVariant('medium', VARIANTS.medium);
    await createVariant('thumb', VARIANTS.thumb);

    return outputs;
}

async function processDoc(doc) {
    const candidates = sourceCandidates(doc);
    const sourceFile = await findExistingFile(candidates);
    if (!sourceFile) {
        return { status: 'missing-source', docId: doc._id, base: parseBaseName(doc) };
    }

    const inputBuffer = await fsPromises.readFile(sourceFile);
    const hash = crypto.createHash('sha256').update(inputBuffer).digest('hex');

    const outputs = await stampAndVariants(inputBuffer, parseBaseName(doc));
    if (APPLY) {
        for (const { filename, buffer } of Object.values(outputs)) {
            await fsPromises.writeFile(path.join(UPLOAD_DIR, filename), buffer);
        }
        doc.path = path.posix.join('uploads', outputs.main.filename);
        doc.variants = {
            medium: path.posix.join('uploads', outputs.medium.filename),
            thumb: path.posix.join('uploads', outputs.thumb.filename),
        };
        doc.hash = doc.hash || hash;
        await doc.save();
    }

    return { status: 'processed', docId: doc._id, base: parseBaseName(doc) };
}

async function main() {
    await mongoose.connect(MONGO_URI);
    console.log(`Connected to Mongo: ${MONGO_URI}`);

    const docs = await Photo.find({});
    console.log(`Found ${docs.length} photo docs. APPLY=${APPLY ? 'yes' : 'no (dry run)'}`);

    const results = { processed: 0, missing: 0 };
    for (const doc of docs) {
        try {
            const res = await processDoc(doc);
            if (res.status === 'processed') results.processed++;
            else results.missing++;
        } catch (err) {
            console.error(`Error processing doc ${doc._id}:`, err.message || err);
            results.missing++;
        }
    }

    console.log(`Done. Processed: ${results.processed}. Skipped (no source/errors): ${results.missing}.`);
    await mongoose.disconnect();
}

main().catch(err => {
    console.error(err);
    process.exit(1);
});