<?php
/**
 * Protocol Droid API Router
 * Handles all /api/* requests. Frontend is served from /frontend/.
 */

header('Content-Type: application/json');
header('X-Content-Type-Options: nosniff');

// CORS — same-origin only; do not reflect arbitrary origins
$origin = $_SERVER['HTTP_ORIGIN'] ?? '';
$expected_host = $_SERVER['HTTP_HOST'] ?? '';
if ($origin) {
    $origin_host = parse_url($origin, PHP_URL_HOST);
    if ($origin_host === $expected_host) {
        header('Access-Control-Allow-Origin: ' . $origin);
        header('Vary: Origin');
    }
}
header('Access-Control-Allow-Methods: GET, POST, PUT, DELETE, OPTIONS');
header('Access-Control-Allow-Headers: Content-Type');
header('Access-Control-Allow-Credentials: true');

if ($_SERVER['REQUEST_METHOD'] === 'OPTIONS') {
    http_response_code(204);
    exit;
}

require_once __DIR__ . '/db.php';
require_once __DIR__ . '/auth.php';
require_once __DIR__ . '/config.php';
require_once __DIR__ . '/yaml.php';

// Auto-init database on first request
if (!defined('DB_INITIALIZED')) {
    db_init();
    define('DB_INITIALIZED', true);
}

// CSRF protection on all state-changing requests
check_csrf();

// --- Helpers ---

function json_body(): array {
    $raw = file_get_contents('php://input');
    $data = json_decode($raw, true);
    return is_array($data) ? $data : [];
}

function respond(int $code, array $data): void {
    http_response_code($code);
    echo json_encode($data);
    exit;
}

function parse_path(): array {
    $uri = $_SERVER['REQUEST_URI'] ?? '/';
    $path = parse_url($uri, PHP_URL_PATH);
    $path = preg_replace('#^/api#', '', $path);
    $path = trim($path, '/');
    return $path === '' ? [] : explode('/', $path);
}

function json_decode_field(?string $val): array {
    if (!$val) return [];
    $decoded = json_decode($val, true);
    return is_array($decoded) ? $decoded : [];
}

function validate_visibility(?string $v): string {
    if (!in_array($v, ['public', 'private', 'unlisted'], true)) return 'public';
    return $v;
}

function sanitize_slug(string $s): string {
    return preg_replace('/[^A-Za-z0-9._-]/', '', $s);
}

function format_protocol(array $row): array {
    return [
        'slug' => $row['slug'],
        'title' => $row['title'],
        'description' => $row['description'] ?? '',
        'source' => $row['source'] ?? '',
        'source_url' => $row['source_url'] ?? '',
        'tags' => json_decode_field($row['tags'] ?? null),
        'forked_from' => $row['forked_from'] ?? null,
        'image' => $row['image'] ?? null,
        'steps' => json_decode_field($row['steps'] ?? null),
        'outcome' => $row['outcome'] ?? '',
        'practice' => $row['practice'] ?? '',
        'author' => $row['author_username'] ?? null,
        'author_id' => $row['author_id'] ?? null,
        'visibility' => $row['visibility'] ?? 'public',
        'created_at' => $row['created_at'] ?? null,
        'updated_at' => $row['updated_at'] ?? null,
    ];
}

function format_collection(array $row, array $items): array {
    return [
        'slug' => $row['slug'],
        'title' => $row['title'],
        'description' => $row['description'] ?? '',
        'source' => $row['source'] ?? '',
        'image' => $row['image'] ?? null,
        'author' => $row['author_username'] ?? null,
        'author_id' => $row['author_id'] ?? null,
        'visibility' => $row['visibility'] ?? 'public',
        'items' => array_map(fn($i) => [
            'type' => $i['item_type'],
            'slug' => $i['item_slug'],
        ], $items),
        'created_at' => $row['created_at'] ?? null,
        'updated_at' => $row['updated_at'] ?? null,
    ];
}

function format_collection_summary(array $row, int $item_count): array {
    return [
        'slug' => $row['slug'],
        'title' => $row['title'],
        'description' => $row['description'] ?? '',
        'source' => $row['source'] ?? '',
        'image' => $row['image'] ?? null,
        'author' => $row['author_username'] ?? null,
        'author_id' => $row['author_id'] ?? null,
        'visibility' => $row['visibility'] ?? 'public',
        'item_count' => $item_count,
        'created_at' => $row['created_at'] ?? null,
        'updated_at' => $row['updated_at'] ?? null,
    ];
}

// --- Routing ---

$parts = parse_path();
$method = $_SERVER['REQUEST_METHOD'];

// Empty path = API root
if (empty($parts)) {
    respond(200, [
        'name' => 'Protocol Droid API',
        'version' => '0.2.0',
        'endpoints' => '/api/protocols, /api/collections, /api/auth/*, /api/users/*',
    ]);
}

// --- Auth routes ---
if ($parts[0] === 'auth') {
    $action = $parts[1] ?? '';
    if ($action === 'register' && $method === 'POST') handle_register();
    elseif ($action === 'login' && $method === 'POST') handle_login();
    elseif ($action === 'logout' && $method === 'POST') handle_logout();
    elseif ($action === 'me' && $method === 'GET') handle_me();
    elseif ($action === 'sso' && $method === 'POST') handle_sso_callback();
    else respond(404, ['error' => 'Unknown auth endpoint']);
}

// --- Config ---
if ($parts[0] === 'config' && $method === 'GET') {
    respond(200, merged_config());
}

// --- Protocols ---
if ($parts[0] === 'protocols') {
    $slug = $parts[1] ?? null;

    if (!$slug) {
        // List protocols
        if ($method !== 'GET') respond(405, ['error' => 'Method not allowed']);

        $where = "WHERE p.visibility = 'public'";
        $params = [];

        $tag = $_GET['tag'] ?? null;
        if ($tag) {
            // Use JSON_CONTAINS for accurate tag matching (MySQL 5.7+)
            $where .= " AND JSON_CONTAINS(p.tags, JSON_QUOTE(?))";
            $params[] = $tag;
        }

        $q = $_GET['q'] ?? null;
        if ($q) {
            $where .= " AND (p.title LIKE ? OR p.description LIKE ? OR p.source LIKE ?)";
            $params = array_merge($params, ["%$q%", "%$q%", "%$q%"]);
        }

        $sql = "SELECT p.*, u.username AS author_username
                FROM protocols p LEFT JOIN users u ON p.author_id = u.id
                $where ORDER BY p.created_at DESC";
        $rows = db_all($sql, $params);
        respond(200, array_map('format_protocol', $rows));
    }

    // YAML export
    if (($parts[2] ?? '') === 'yaml' && $method === 'GET') {
        $row = db_one("SELECT * FROM protocols WHERE slug = ?", [$slug]);
        if (!$row) respond(404, ['error' => 'Protocol not found']);
        $safe_slug = sanitize_slug($slug);
        header('Content-Type: text/yaml');
        header('Content-Disposition: attachment; filename="' . $safe_slug . '.yaml"');
        echo protocol_to_yaml($row);
        exit;
    }

    // Votes for a protocol
    if (($parts[2] ?? '') === 'votes' && $method === 'GET') {
        // Check protocol exists and is public (or user is author/admin)
        $row = db_one("SELECT * FROM protocols WHERE slug = ?", [$slug]);
        if (!$row) respond(404, ['error' => 'Protocol not found']);
        $user = current_user();
        if ($row['visibility'] !== 'public' && (!$user || ($row['author_id'] != $user['id'] && $user['role'] !== 'admin'))) {
            respond(404, ['error' => 'Protocol not found']);
        }
        $votes = db_all(
            "SELECT v.value, v.comment, v.created_at, u.username FROM votes v LEFT JOIN users u ON v.user_id = u.id WHERE v.protocol_slug = ?",
            [$slug]
        );
        $score = array_sum(array_column($votes, 'value'));
        respond(200, ['score' => $score, 'votes' => $votes]);
    }

    // Single protocol — enforce visibility
    if ($method === 'GET') {
        $row = db_one(
            "SELECT p.*, u.username AS author_username FROM protocols p LEFT JOIN users u ON p.author_id = u.id WHERE p.slug = ?",
            [$slug]
        );
        if (!$row) respond(404, ['error' => 'Protocol not found']);
        $user = current_user();
        if ($row['visibility'] !== 'public' && (!$user || ($row['author_id'] != $user['id'] && $user['role'] !== 'admin'))) {
            respond(404, ['error' => 'Protocol not found']);
        }
        respond(200, format_protocol($row));
    }

    // Create protocol
    if ($method === 'POST') {
        $user = require_member();
        $data = json_body();

        $new_slug = ensure_unique_slug($data['slug'] ?? slugify($data['title'] ?? 'untitled'));
        $id = db_insert('protocols', [
            'slug' => $new_slug,
            'title' => substr($data['title'] ?? '', 0, 255),
            'description' => $data['description'] ?? '',
            'source' => $data['source'] ?? ('@' . $user['username']),
            'source_url' => substr($data['source_url'] ?? '', 0, 500),
            'tags' => json_encode(array_slice($data['tags'] ?? [], 0, 20)),
            'forked_from' => $data['forked_from'] ?? null,
            'image' => $data['image'] ?? null,
            'steps' => json_encode(array_slice($data['steps'] ?? [], 0, 50)),
            'outcome' => $data['outcome'] ?? '',
            'practice' => $data['practice'] ?? '',
            'author_id' => $user['id'],
            'visibility' => validate_visibility($data['visibility'] ?? 'public'),
        ]);
        $row = db_one("SELECT p.*, u.username AS author_username FROM protocols p LEFT JOIN users u ON p.author_id = u.id WHERE p.id = ?", [$id]);
        respond(201, format_protocol($row));
    }

    // Update protocol — auth before existence check
    if ($method === 'PUT') {
        $user = require_auth();
        $row = db_one("SELECT * FROM protocols WHERE slug = ?", [$slug]);
        if (!$row) respond(404, ['error' => 'Protocol not found']);
        if ($row['author_id'] != $user['id'] && $user['role'] !== 'admin') {
            respond(403, ['error' => 'You can only edit your own protocols']);
        }

        $data = json_body();
        $updates = [];
        foreach (['title', 'description', 'source', 'source_url', 'forked_from', 'image', 'outcome', 'practice'] as $field) {
            if (array_key_exists($field, $data)) $updates[$field] = $data[$field];
        }
        if (array_key_exists('tags', $data)) $updates['tags'] = json_encode(array_slice($data['tags'] ?? [], 0, 20));
        if (array_key_exists('steps', $data)) $updates['steps'] = json_encode(array_slice($data['steps'] ?? [], 0, 50));
        if (array_key_exists('visibility', $data)) $updates['visibility'] = validate_visibility($data['visibility']);
        if ($updates) {
            db_update('protocols', $updates, 'slug = ?', [$slug]);
        }
        $row = db_one("SELECT p.*, u.username AS author_username FROM protocols p LEFT JOIN users u ON p.author_id = u.id WHERE p.slug = ?", [$slug]);
        respond(200, format_protocol($row));
    }

    // Delete protocol — auth before existence check
    if ($method === 'DELETE') {
        $user = require_auth();
        $row = db_one("SELECT * FROM protocols WHERE slug = ?", [$slug]);
        if (!$row) respond(404, ['error' => 'Protocol not found']);
        if ($row['author_id'] != $user['id'] && $user['role'] !== 'admin') {
            respond(403, ['error' => 'You can only delete your own protocols']);
        }

        // Clean up orphaned votes and collection items
        db_query("DELETE FROM votes WHERE protocol_slug = ?", [$slug]);
        db_query("DELETE FROM collection_items WHERE item_type = 'protocol' AND item_slug = ?", [$slug]);
        db_query("DELETE FROM protocols WHERE slug = ?", [$slug]);
        respond(200, ['ok' => true]);
    }

    respond(405, ['error' => 'Method not allowed']);
}

// --- Collections ---
if ($parts[0] === 'collections') {
    $slug = $parts[1] ?? null;

    if (!$slug) {
        // List collections
        if ($method === 'GET') {
            $rows = db_all(
                "SELECT c.*, u.username AS author_username FROM collections c LEFT JOIN users u ON c.author_id = u.id WHERE c.visibility = 'public' ORDER BY c.created_at DESC"
            );
            $result = [];
            foreach ($rows as $row) {
                $items = db_all("SELECT * FROM collection_items WHERE collection_id = ?", [$row['id']]);
                $result[] = format_collection_summary($row, count($items));
            }
            respond(200, $result);
        }
        // Create collection
        if ($method === 'POST') {
            $user = require_member();
            $data = json_body();
            $new_slug = ensure_unique_slug($data['slug'] ?? slugify($data['title'] ?? 'untitled'));
            $id = db_insert('collections', [
                'slug' => $new_slug,
                'title' => substr($data['title'] ?? '', 0, 255),
                'description' => $data['description'] ?? '',
                'source' => $data['source'] ?? ('@' . $user['username']),
                'image' => $data['image'] ?? null,
                'author_id' => $user['id'],
                'visibility' => validate_visibility($data['visibility'] ?? 'public'),
            ]);
            $position = 0;
            foreach (($data['items'] ?? []) as $item) {
                db_insert('collection_items', [
                    'collection_id' => $id,
                    'item_type' => $item['type'] ?? 'protocol',
                    'item_slug' => $item['slug'] ?? '',
                    'position' => $position++,
                ]);
            }
            $row = db_one("SELECT c.*, u.username AS author_username FROM collections c LEFT JOIN users u ON c.author_id = u.id WHERE c.id = ?", [$id]);
            $items = db_all("SELECT * FROM collection_items WHERE collection_id = ? ORDER BY position", [$id]);
            respond(201, format_collection($row, $items));
        }
        respond(405, ['error' => 'Method not allowed']);
    }

    // Single collection — enforce visibility
    if ($method === 'GET') {
        $row = db_one(
            "SELECT c.*, u.username AS author_username FROM collections c LEFT JOIN users u ON c.author_id = u.id WHERE c.slug = ?",
            [$slug]
        );
        if (!$row) respond(404, ['error' => 'Collection not found']);
        $user = current_user();
        if ($row['visibility'] !== 'public' && (!$user || ($row['author_id'] != $user['id'] && $user['role'] !== 'admin'))) {
            respond(404, ['error' => 'Collection not found']);
        }
        $items = db_all("SELECT * FROM collection_items WHERE collection_id = ? ORDER BY position", [$row['id']]);
        respond(200, format_collection($row, $items));
    }

    // Update collection — auth before existence check
    if ($method === 'PUT') {
        $user = require_auth();
        $row = db_one("SELECT * FROM collections WHERE slug = ?", [$slug]);
        if (!$row) respond(404, ['error' => 'Collection not found']);
        if ($row['author_id'] != $user['id'] && $user['role'] !== 'admin') {
            respond(403, ['error' => 'You can only edit your own collections']);
        }

        $data = json_body();
        $updates = [];
        foreach (['title', 'description', 'source', 'image'] as $field) {
            if (array_key_exists($field, $data)) $updates[$field] = $data[$field];
        }
        if (array_key_exists('visibility', $data)) $updates['visibility'] = validate_visibility($data['visibility']);
        if ($updates) db_update('collections', $updates, 'slug = ?', [$slug]);

        // Update items if provided
        if (isset($data['items'])) {
            $col_id = $row['id'];
            db_query("DELETE FROM collection_items WHERE collection_id = ?", [$col_id]);
            $position = 0;
            foreach ($data['items'] as $item) {
                db_insert('collection_items', [
                    'collection_id' => $col_id,
                    'item_type' => $item['type'] ?? 'protocol',
                    'item_slug' => $item['slug'] ?? '',
                    'position' => $position++,
                ]);
            }
        }

        $row = db_one("SELECT c.*, u.username AS author_username FROM collections c LEFT JOIN users u ON c.author_id = u.id WHERE c.slug = ?", [$slug]);
        $items = db_all("SELECT * FROM collection_items WHERE collection_id = ? ORDER BY position", [$row['id']]);
        respond(200, format_collection($row, $items));
    }

    // Delete collection — auth before existence check
    if ($method === 'DELETE') {
        $user = require_auth();
        $row = db_one("SELECT * FROM collections WHERE slug = ?", [$slug]);
        if (!$row) respond(404, ['error' => 'Collection not found']);
        if ($row['author_id'] != $user['id'] && $user['role'] !== 'admin') {
            respond(403, ['error' => 'You can only delete your own collections']);
        }
        db_query("DELETE FROM collection_items WHERE collection_id = ?", [$row['id']]);
        db_query("DELETE FROM collections WHERE slug = ?", [$slug]);
        respond(200, ['ok' => true]);
    }

    respond(405, ['error' => 'Method not allowed']);
}

// --- Users ---
if ($parts[0] === 'users') {
    $username = $parts[1] ?? null;
    if (!$username || $method !== 'GET') respond(404, ['error' => 'Unknown endpoint']);

    $user = db_one("SELECT id, username, display_name, bio, created_at FROM users WHERE username = ?", [$username]);
    if (!$user) respond(404, ['error' => 'User not found']);

    // Fetch full protocol data for user's public protocols
    $protocols = db_all(
        "SELECT p.*, u.username AS author_username FROM protocols p LEFT JOIN users u ON p.author_id = u.id WHERE p.author_id = ? AND p.visibility = 'public' ORDER BY p.created_at DESC",
        [$user['id']]
    );
    $collections = db_all("SELECT slug, title, description FROM collections WHERE author_id = ? AND visibility = 'public' ORDER BY created_at DESC", [$user['id']]);

    respond(200, [
        'user' => $user,
        'protocols' => array_map('format_protocol', $protocols),
        'collections' => $collections,
    ]);
}

// --- Votes ---
if ($parts[0] === 'votes' && $method === 'POST') {
    $user = require_member();
    $data = json_body();
    $protocol_slug = $data['protocol_slug'] ?? '';
    // Constrain value to -1, 0, or 1
    $value = (int)($data['value'] ?? 1);
    $value = $value > 0 ? 1 : ($value < 0 ? -1 : 0);
    $comment = substr($data['comment'] ?? '', 0, 1000);

    // Check protocol exists and is public
    $proto = db_one("SELECT * FROM protocols WHERE slug = ?", [$protocol_slug]);
    if (!$proto) respond(404, ['error' => 'Protocol not found']);
    if ($proto['visibility'] !== 'public') respond(404, ['error' => 'Protocol not found']);

    // Upsert vote
    db_query(
        "INSERT INTO votes (user_id, protocol_slug, value, comment) VALUES (?, ?, ?, ?)
         ON DUPLICATE KEY UPDATE value = VALUES(value), comment = VALUES(comment)",
        [$user['id'], $protocol_slug, $value, $comment]
    );
    respond(200, ['ok' => true]);
}

// --- Import / Export / Seed ---
if ($parts[0] === 'export' && $method === 'GET') {
    require_admin();
    $protocols = db_all("SELECT * FROM protocols WHERE visibility = 'public'");
    $output = "# Protocol Droid Export\n\n";
    foreach ($protocols as $p) {
        $output .= "---\n\n" . protocol_to_yaml($p) . "\n";
    }
    header('Content-Type: text/yaml');
    header('Content-Disposition: attachment; filename="protocol-droid-export.yaml"');
    echo $output;
    exit;
}

if ($parts[0] === 'import' && $method === 'POST') {
    require_admin();
    $data = json_body();
    $yaml_text = $data['yaml'] ?? '';
    $parsed = parse_protocol_yaml($yaml_text);
    if (!$parsed) respond(400, ['error' => 'Could not parse YAML']);

    $parsed['author_id'] = current_user()['id'];
    $parsed['slug'] = ensure_unique_slug($parsed['slug']);
    $parsed['visibility'] = validate_visibility($parsed['visibility'] ?? 'public');
    $id = db_insert('protocols', $parsed);
    respond(201, ['id' => $id, 'slug' => $parsed['slug']]);
}

if ($parts[0] === 'seed' && $method === 'POST') {
    require_admin();
    $seeds_dir = __DIR__ . '/../seeds';
    if (!is_dir($seeds_dir)) respond(404, ['error' => 'No seeds directory']);

    $count = 0;
    foreach (glob($seeds_dir . '/*.yaml') as $file) {
        $yaml_text = file_get_contents($file);
        $parsed = parse_protocol_yaml($yaml_text);
        if (!$parsed) continue;

        if (db_one("SELECT slug FROM protocols WHERE slug = ?", [$parsed['slug']])) continue;

        db_insert('protocols', $parsed);
        $count++;
    }
    respond(200, ['imported' => $count]);
}

respond(404, ['error' => 'Unknown endpoint: /' . implode('/', $parts)]);