// A stub of the parts of the Gitea API that publish.ps1 and install.ps1 use.
//
// The point is to prove the real scripts work: that the token header is sent, that the
// multipart upload delivers the .vsix byte-for-byte (a zip, so any encoding step would
// corrupt it), that re-publishing replaces assets instead of duplicating them, and that
// the download survives a redirect with the auth header intact.

const http = require('http');
const crypto = require('crypto');

const PORT = Number(process.env.PORT || 5602);
const TOKEN = 'TESTTOKEN';

let nextId = 100;
const releases = [];        // { id, tag_name, name, body, assets: [] }
const blobs = new Map();    // uuid -> Buffer
const log = [];

function sha256(buffer) {
    return crypto.createHash('sha256').update(buffer).digest('hex').toUpperCase();
}

function authorized(request) {
    return request.headers.authorization === `token ${TOKEN}`;
}

function send(response, status, payload) {
    const body = payload === undefined ? '' : JSON.stringify(payload);
    response.writeHead(status, { 'Content-Type': 'application/json' });
    response.end(body);
}

function readBody(request) {
    return new Promise((resolve, reject) => {
        const chunks = [];
        request.on('data', chunk => chunks.push(chunk));
        request.on('end', () => resolve(Buffer.concat(chunks)));
        request.on('error', reject);
    });
}

/** The one file out of a multipart/form-data body, as raw bytes. */
function parseMultipart(buffer, contentType) {
    const match = /boundary=(?:"([^"]+)"|([^;]+))/i.exec(contentType || '');
    if (!match) { return null; }
    const boundary = Buffer.from(`--${match[1] || match[2]}`);

    const parts = [];
    let at = buffer.indexOf(boundary);
    while (at >= 0) {
        const from = at + boundary.length;
        const next = buffer.indexOf(boundary, from);
        if (next < 0) { break; }
        parts.push(buffer.slice(from, next));
        at = next;
    }

    for (const part of parts) {
        const split = part.indexOf('\r\n\r\n');
        if (split < 0) { continue; }
        const headers = part.slice(0, split).toString('latin1');
        // Trailing CRLF belongs to the delimiter, not the content.
        let content = part.slice(split + 4);
        if (content.slice(-2).toString('latin1') === '\r\n') {
            content = content.slice(0, -2);
        }
        // Values may be unquoted: .NET Framework's MultipartFormDataContent writes
        // name=attachment, and Go's mime/multipart (what Gitea uses) accepts both.
        const name = /\bname=(?:"([^"]*)"|([^;\s]+))/i.exec(headers);
        const filename = /\bfilename=(?:"([^"]*)"|([^;\s]+))/i.exec(headers);
        const fieldName = name ? (name[1] !== undefined ? name[1] : name[2]) : null;
        if (fieldName === 'attachment') {
            return {
                content,
                filename: filename ? (filename[1] !== undefined ? filename[1] : filename[2]) : null,
                headers: headers.trim(),
            };
        }
    }
    return null;
}

const server = http.createServer(async (request, response) => {
    const url = new URL(request.url, 'http://localhost');
    const path = url.pathname;
    log.push(`${request.method} ${request.url}`);

    // Serving an attachment: what browser_download_url points at.
    let hit = /^\/attachments\/([^/]+)$/.exec(path);
    if (hit && request.method === 'GET') {
        // Redirect once, so the client has to carry the auth header across it.
        response.writeHead(302, { Location: `/files/${hit[1]}` });
        return response.end();
    }
    hit = /^\/files\/([^/]+)$/.exec(path);
    if (hit && request.method === 'GET') {
        if (!authorized(request)) {
            log.push('  !! download had no token');
            return send(response, 401, { message: 'token required on download' });
        }
        const blob = blobs.get(hit[1]);
        if (!blob) { return send(response, 404, { message: 'no such attachment' }); }
        response.writeHead(200, {
            'Content-Type': 'application/octet-stream',
            'Content-Length': blob.length,
        });
        return response.end(blob);
    }

    // Test-only: lets the harness assert on what the server actually received.
    if (path === '/__state') {
        return send(response, 200, {
            log,
            releases: releases.map(release => ({
                id: release.id,
                tag_name: release.tag_name,
                name: release.name,
                assets: release.assets.map(asset => ({
                    id: asset.id,
                    name: asset.name,
                    size: asset.size,
                    sha256: asset.sha256,
                    uploadFilename: asset.uploadFilename,
                })),
            })),
        });
    }

    if (!authorized(request)) {
        log.push('  !! missing or wrong token');
        return send(response, 401, { message: 'token required' });
    }

    const api = /^\/api\/v1\/repos\/([^/]+)\/([^/]+)\/releases(.*)$/.exec(path);
    if (!api) { return send(response, 404, { message: `unhandled ${path}` }); }
    const rest = api[3];

    // GET /releases/tags/:tag
    hit = /^\/tags\/(.+)$/.exec(rest);
    if (hit && request.method === 'GET') {
        const tag = decodeURIComponent(hit[1]);
        const release = releases.find(candidate => candidate.tag_name === tag);
        if (!release) { return send(response, 404, { message: 'release not found' }); }
        return send(response, 200, release);
    }

    // POST /releases
    if (rest === '' && request.method === 'POST') {
        const body = JSON.parse((await readBody(request)).toString('utf8') || '{}');
        if (!body.tag_name) { return send(response, 422, { message: 'tag_name required' }); }
        const release = {
            id: nextId++,
            tag_name: body.tag_name,
            name: body.name || body.tag_name,
            body: body.body || '',
            draft: !!body.draft,
            prerelease: !!body.prerelease,
            target_commitish: body.target_commitish || 'main',
            assets: [],
        };
        releases.push(release);
        return send(response, 201, release);
    }

    // POST /releases/:id/assets?name=...
    hit = /^\/(\d+)\/assets$/.exec(rest);
    if (hit && request.method === 'POST') {
        const release = releases.find(candidate => candidate.id === Number(hit[1]));
        if (!release) { return send(response, 404, { message: 'no such release' }); }

        const raw = await readBody(request);
        const part = parseMultipart(raw, request.headers['content-type']);
        if (!part) {
            const preview = raw.slice(0, 400).toString('latin1').replace(/\r\n/g, '\\r\\n');
            log.push(`  !! no attachment field. content-type=${request.headers['content-type']}`);
            log.push(`  !! body starts: ${preview}`);
            return send(response, 400, { message: 'expected multipart with an attachment field' });
        }
        log.push(`  disposition: ${part.headers.replace(/\r\n/g, ' | ')}`);

        const name = url.searchParams.get('name') || part.filename || 'unnamed';
        const uuid = crypto.randomBytes(8).toString('hex');
        blobs.set(uuid, part.content);
        const asset = {
            id: nextId++,
            name,
            size: part.content.length,
            sha256: sha256(part.content),
            uploadFilename: part.filename,
            browser_download_url: `http://127.0.0.1:${PORT}/attachments/${uuid}`,
        };
        release.assets.push(asset);
        return send(response, 201, asset);
    }

    // DELETE /releases/:id/assets/:assetId
    hit = /^\/(\d+)\/assets\/(\d+)$/.exec(rest);
    if (hit && request.method === 'DELETE') {
        const release = releases.find(candidate => candidate.id === Number(hit[1]));
        if (!release) { return send(response, 404, { message: 'no such release' }); }
        const before = release.assets.length;
        release.assets = release.assets.filter(asset => asset.id !== Number(hit[2]));
        if (release.assets.length === before) {
            return send(response, 404, { message: 'no such asset' });
        }
        response.writeHead(204);
        return response.end();
    }

    return send(response, 404, { message: `unhandled ${request.method} ${path}` });
});

server.listen(PORT, '127.0.0.1', () => {
    console.log(`fake gitea on http://127.0.0.1:${PORT} (token ${TOKEN})`);
});