// =======================================================================
// Notes Application - API Client Module (Native ES Module)
// =======================================================================

// Persistent session: auto-inject Authorization header if token exists in localStorage
const originalFetch = window.fetch;
window.fetch = function(url, options = {}) {
    const token = localStorage.getItem('notes_token');
    if (token && typeof url === 'string' && url.startsWith('/api/')) {
        options.headers = options.headers || {};
        if (options.headers instanceof Headers) {
            if (!options.headers.has('Authorization')) {
                options.headers.set('Authorization', `Bearer ${token}`);
            }
        } else if (Array.isArray(options.headers)) {
            if (!options.headers.some(([k]) => k.toLowerCase() === 'authorization')) {
                options.headers.push(['Authorization', `Bearer ${token}`]);
            }
        } else {
            if (!options.headers['Authorization']) {
                options.headers['Authorization'] = `Bearer ${token}`;
            }
        }
    }
    return originalFetch.call(this, url, options);
};

export const api = {
    // Auth endpoints
    auth: {
        async check() {
            const resp = await fetch('/api/me');
            if (resp.ok) {
                return await resp.json();
            }
            return null;
        },
        async login(username, password) {
            return await fetch('/api/login', {
                method: 'POST',
                headers: { 'Content-Type': 'application/json' },
                body: JSON.stringify({ username, password })
            });
        },
        async logout() {
            return await fetch('/api/logout', { method: 'POST' });
        },
        async changePassword(currentPassword, newPassword) {
            return await fetch('/api/change-password', {
                method: 'POST',
                headers: { 'Content-Type': 'application/json' },
                body: JSON.stringify({
                    old_password: currentPassword,
                    new_password: newPassword
                })
            });
        }
    },

    // Cards & Vocabulary
    cards: {
        async getAll(params = {}) {
            const qs = new URLSearchParams(params).toString();
            const url = qs ? `/api/cards?${qs}` : '/api/cards';
            const resp = await fetch(url);
            return resp.ok ? await resp.json() : [];
        },
        async lookup(term) {
            return await api.lookup.search(term);
        },
        async create(payload) {
            return await fetch('/api/cards', {
                method: 'POST',
                headers: { 'Content-Type': 'application/json' },
                body: JSON.stringify(payload)
            });
        },
        async update(id, payload) {
            return await fetch(`/api/cards/${id}`, {
                method: 'PUT',
                headers: { 'Content-Type': 'application/json' },
                body: JSON.stringify(payload)
            });
        },
        async delete(id) {
            return await fetch(`/api/cards/${id}`, { method: 'DELETE' });
        },
        async batch(payload) {
            return await fetch('/api/cards/batch', {
                method: 'POST',
                headers: { 'Content-Type': 'application/json' },
                body: JSON.stringify(payload)
            });
        }
    },

    // Dictionary Lookup & AI Sentence Translation
    lookup: {
        async search(term) {
            const resp = await fetch(`/api/lookup?term=${encodeURIComponent(term)}`);
            if (resp.ok) {
                return await resp.json();
            }
            throw new Error(`Lookup failed: ${resp.status}`);
        },
        async translateSentence(sentence, targetWord = '') {
            const resp = await fetch('/api/translate-sentence', {
                method: 'POST',
                headers: { 'Content-Type': 'application/json' },
                body: JSON.stringify({
                    sentence: sentence,
                    target_word: targetWord
                })
            });
            if (resp.ok) {
                return await resp.json();
            }
            throw new Error(`Sentence translation failed: ${resp.status}`);
        },
        async getAiStatus() {
            const resp = await fetch('/api/ai/status');
            return resp.ok ? await resp.json() : { online: false, models: [] };
        }
    },

    // Collections & Tags
    collections: {
        async getAll() {
            const resp = await fetch('/api/collections');
            return resp.ok ? await resp.json() : [];
        }
    },
    tags: {
        async getAll() {
            const resp = await fetch('/api/tags');
            return resp.ok ? await resp.json() : [];
        }
    },

    // Statistics & Analytics
    stats: {
        async getStats() {
            const resp = await fetch('/api/stats');
            return resp.ok ? await resp.json() : null;
        },
        async getSrsStats() {
            const resp = await fetch('/api/srs/stats');
            return resp.ok ? await resp.json() : null;
        },
        async getHeatmap(days = 180) {
            const resp = await fetch(`/api/srs/activity-heatmap?days=${days}`);
            return resp.ok ? await resp.json() : { days: [] };
        }
    },

    // SRS Spaced Repetition
    srs: {
        async getQueue(forceAll = false, tagFilter = null) {
            let url = '/api/srs/queue?limit=50';
            if (forceAll) url += '&force_all=true';
            if (tagFilter) url += `&tag=${encodeURIComponent(tagFilter)}`;
            const resp = await fetch(url);
            return resp.ok ? await resp.json() : [];
        },
        async submitReview(cardId, rating) {
            return await fetch('/api/srs/review', {
                method: 'POST',
                headers: { 'Content-Type': 'application/json' },
                body: JSON.stringify({ card_id: cardId, rating })
            });
        }
    },

    // Bookshelf & Reader
    books: {
        async getAll() {
            const resp = await fetch('/api/books');
            return resp.ok ? await resp.json() : [];
        },
        async get(id) {
            const resp = await fetch(`/api/books/${id}`);
            if (resp.ok) return await resp.json();
            throw new Error(`Failed to load book ${id}: ${resp.status}`);
        },
        async uploadFile(formData) {
            return await fetch('/api/books', {
                method: 'POST',
                body: formData
            });
        },
        async createManual(payload) {
            return await fetch('/api/books', {
                method: 'POST',
                headers: { 'Content-Type': 'application/json' },
                body: JSON.stringify(payload)
            });
        },
        async delete(id) {
            return await fetch(`/api/books/${id}`, { method: 'DELETE' });
        },
        async saveProgress(bookId, payload) {
            return await fetch(`/api/books/${bookId}/progress`, {
                method: 'PUT',
                headers: { 'Content-Type': 'application/json' },
                body: JSON.stringify(payload)
            });
        }
    }
};