// ==========================================
// Switchboard Backend API Client
// ==========================================
// Handles auth + chat/message CRUD against the
// Switchboard backend. Token refresh is automatic.
// ==========================================

const Backend = {
    baseUrl: '',
    accessToken: null,
    refreshToken: null,
    user: null,
    _refreshPromise: null,

    // ── Connection ──────────────────────────

    get isConnected() {
        return !!(this.baseUrl && this.accessToken);
    },

    get isManaged() {
        return this.isConnected;
    },

    // ── Init ────────────────────────────────

    init() {
        // Auto-detect: if we're served from a domain with /api/v1,
        // the backend is co-located. Otherwise check saved URL.
        const saved = Storage.get('switchboard_backend');
        if (saved) {
            this.baseUrl = saved.baseUrl || '';
            this.accessToken = saved.accessToken || null;
            this.refreshToken = saved.refreshToken || null;
            this.user = saved.user || null;
        }
    },

    save() {
        Storage.set('switchboard_backend', {
            baseUrl: this.baseUrl,
            accessToken: this.accessToken,
            refreshToken: this.refreshToken,
            user: this.user
        });
    },

    clear() {
        this.accessToken = null;
        this.refreshToken = null;
        this.user = null;
        this.save();
    },

    // ── Auth ────────────────────────────────

    async register(username, email, password) {
        const data = await this._fetch('/api/v1/auth/register', {
            method: 'POST',
            body: JSON.stringify({ username, email, password })
        }, true);
        this._setAuth(data);
        return data;
    },

    async login(login, password) {
        const data = await this._fetch('/api/v1/auth/login', {
            method: 'POST',
            body: JSON.stringify({ login, password })
        }, true);
        this._setAuth(data);
        return data;
    },

    async logout() {
        try {
            await this._fetch('/api/v1/auth/logout', {
                method: 'POST',
                body: JSON.stringify({ refresh_token: this.refreshToken })
            }, true);
        } catch (e) {
            // Best-effort
        }
        this.clear();
    },

    async refresh() {
        // Deduplicate concurrent refresh calls
        if (this._refreshPromise) return this._refreshPromise;

        this._refreshPromise = (async () => {
            try {
                const data = await this._fetch('/api/v1/auth/refresh', {
                    method: 'POST',
                    body: JSON.stringify({ refresh_token: this.refreshToken })
                }, true);
                this._setAuth(data);
                return true;
            } catch (e) {
                this.clear();
                return false;
            } finally {
                this._refreshPromise = null;
            }
        })();

        return this._refreshPromise;
    },

    _setAuth(data) {
        this.accessToken = data.access_token;
        this.refreshToken = data.refresh_token;
        this.user = data.user;
        this.save();
    },

    // ── Health ───────────────────────────────

    async checkHealth(url) {
        try {
            const resp = await fetch(url + '/api/v1/health', {
                signal: AbortSignal.timeout(5000)
            });
            if (!resp.ok) return null;
            return await resp.json();
        } catch (e) {
            return null;
        }
    },

    // ── Chats ───────────────────────────────

    async listChats(page = 1, perPage = 50) {
        return this._authedFetch(`/api/v1/chats?page=${page}&per_page=${perPage}`);
    },

    async createChat(title, model, systemPrompt) {
        const body = { title };
        if (model) body.model = model;
        if (systemPrompt) body.system_prompt = systemPrompt;
        return this._authedFetch('/api/v1/chats', {
            method: 'POST',
            body: JSON.stringify(body)
        });
    },

    async getChat(chatId) {
        return this._authedFetch(`/api/v1/chats/${chatId}`);
    },

    async updateChat(chatId, updates) {
        return this._authedFetch(`/api/v1/chats/${chatId}`, {
            method: 'PUT',
            body: JSON.stringify(updates)
        });
    },

    async deleteChat(chatId) {
        return this._authedFetch(`/api/v1/chats/${chatId}`, {
            method: 'DELETE'
        });
    },

    // ── Messages ────────────────────────────

    async listMessages(chatId, page = 1, perPage = 100) {
        return this._authedFetch(
            `/api/v1/chats/${chatId}/messages?page=${page}&per_page=${perPage}`
        );
    },

    async createMessage(chatId, role, content, model) {
        const body = { role, content };
        if (model) body.model = model;
        return this._authedFetch(`/api/v1/chats/${chatId}/messages`, {
            method: 'POST',
            body: JSON.stringify(body)
        });
    },

    // ── HTTP Layer ──────────────────────────

    async _authedFetch(path, opts = {}) {
        try {
            return await this._fetch(path, {
                ...opts,
                headers: {
                    ...opts.headers,
                    'Authorization': `Bearer ${this.accessToken}`
                }
            });
        } catch (e) {
            // If 401, try refresh once
            if (e.status === 401 && this.refreshToken) {
                const refreshed = await this.refresh();
                if (refreshed) {
                    return this._fetch(path, {
                        ...opts,
                        headers: {
                            ...opts.headers,
                            'Authorization': `Bearer ${this.accessToken}`
                        }
                    });
                }
            }
            throw e;
        }
    },

    async _fetch(path, opts = {}, skipAuth = false) {
        const url = this.baseUrl + path;
        const resp = await fetch(url, {
            ...opts,
            headers: {
                'Content-Type': 'application/json',
                ...opts.headers
            }
        });

        if (!resp.ok) {
            const body = await resp.json().catch(() => ({}));
            const err = new Error(body.error || `HTTP ${resp.status}`);
            err.status = resp.status;
            throw err;
        }

        return resp.json();
    }
};