import type {
    ChatMessageResponse,
    ChatSessionResponse,
    CourseResponse,
    DocumentSource,
} from '@/lib/rag';
import type {
    AdminUser,
    GeneratedApiKey,
    LlmConfig,
    RagConfig,
    RetrievalConfig,
    VectorDbConfig,
} from '@/types/admin';

export type { ChatMessageResponse, ChatSessionResponse, CourseResponse };

export type DocumentResponse = {
    id: string;
    filename: string;
    file_type: string;
    file_size: number;
    status: 'processing' | 'ready' | 'failed';
    course_id: string;
    course_name?: string;
    uploaded_by: string;
    uploader_name?: string;
    summary?: string;
    chunk_count?: number;
    error?: string;
    created_at: string;
    updated_at: string;
};

export type AuthUser = {
    id?: number | string;
    name?: string;
    email?: string;
    role?: string;
    is_active?: boolean;
    is_superuser?: boolean;
    [key: string]: unknown;
};

export class RagApiError extends Error {
    constructor(
        message: string,
        public readonly status: number,
        public readonly data?: unknown,
    ) {
        super(message);
        this.name = 'RagApiError';
    }
}

const BASE_URL =
    (import.meta.env.VITE_RAG_API_BASE_URL as string | undefined)?.replace(
        /\/$/,
        '',
    ) ?? '';

function getAuthToken(): string | null {
    if (typeof document === 'undefined') {
        return null;
    }

    const match = document.cookie.match(
        /(?:^|;\s*)sevima_raghub_auth_token=([^;]*)/,
    );

    return match ? decodeURIComponent(match[1]) : null;
}

function makeHeaders(
    extra: Record<string, string> = {},
): Record<string, string> {
    const token = getAuthToken();

    return {
        Accept: 'application/json',
        ...(token ? { Authorization: `Bearer ${token}` } : {}),
        ...extra,
    };
}

async function buildRagError(response: Response): Promise<RagApiError> {
    let body: unknown = null;
    let message = `${response.status} ${response.statusText}`;

    if (response.status === 429) {
        message = 'Terlalu banyak percobaan. Silakan tunggu beberapa saat sebelum mencoba lagi.';
    }

    try {
        body = await response.json();

        if (body !== null && typeof body === 'object') {
            const b = body as Record<string, unknown>;

            if (typeof b.detail === 'string' && b.detail) {
                message = b.detail;
            } else if (typeof b.message === 'string' && b.message) {
                message = b.message;
            } else if (typeof b.error === 'string' && b.error) {
                message = b.error;
            }
        }
    } catch {
        // ignore
    }

    return new RagApiError(message, response.status, body);
}

async function ragGet<T>(path: string): Promise<T> {
    const response = await fetch(`${BASE_URL}${path}`, {
        headers: makeHeaders(),
    });

    if (!response.ok) {
        throw await buildRagError(response);
    }

    return response.json() as Promise<T>;
}

async function ragJson<T>(
    path: string,
    method: string,
    body: unknown,
): Promise<T> {
    const response = await fetch(`${BASE_URL}${path}`, {
        body: JSON.stringify(body),
        headers: makeHeaders({ 'Content-Type': 'application/json' }),
        method,
    });

    if (!response.ok) {
        throw await buildRagError(response);
    }

    return response.json() as Promise<T>;
}

async function ragDelete(path: string): Promise<void> {
    const response = await fetch(`${BASE_URL}${path}`, {
        headers: makeHeaders(),
        method: 'DELETE',
    });

    if (!response.ok) {
        throw await buildRagError(response);
    }
}

// Courses

export function listCourses(
    page = 1,
    limit = 100,
): Promise<{ data: CourseResponse[] }> {
    return ragGet(`/courses?page=${page}&limit=${limit}`);
}

export function getCourse(courseId: string): Promise<CourseResponse> {
    return ragGet(`/courses/${encodeURIComponent(courseId)}`);
}

export function createCourse(payload: {
    title: string;
    description?: string;
}): Promise<CourseResponse> {
    return ragJson('/courses', 'POST', payload);
}

export function updateCourse(
    courseId: string,
    payload: { title?: string; description?: string },
): Promise<CourseResponse> {
    return ragJson(`/courses/${encodeURIComponent(courseId)}`, 'PUT', payload);
}

export function deleteCourse(courseId: string): Promise<void> {
    return ragDelete(`/courses/${encodeURIComponent(courseId)}`);
}

export function listCourseDocuments(
    courseId: string,
): Promise<{ data: DocumentResponse[] }> {
    return ragGet(`/courses/${encodeURIComponent(courseId)}/documents`);
}

export function deleteDocument(
    courseId: string,
    documentId: string,
): Promise<void> {
    return ragDelete(
        `/courses/${encodeURIComponent(courseId)}/documents/${encodeURIComponent(documentId)}`,
    );
}

export async function uploadDocument(
    courseId: string,
    file: File,
): Promise<void> {
    const token = getAuthToken();
    const formData = new FormData();
    formData.append('file', file);
    formData.append('course_id', courseId);

    const response = await fetch(`${BASE_URL}/documents/upload`, {
        body: formData,
        headers: {
            ...(token ? { Authorization: `Bearer ${token}` } : {}),
        },
        method: 'POST',
    });

    if (!response.ok) {
        throw await buildRagError(response);
    }
}

// Chat Sessions

export function listChatSessions(
    page = 1,
    limit = 20,
): Promise<{ data: ChatSessionResponse[] }> {
    return ragGet(`/chats/sessions?page=${page}&limit=${limit}`);
}

export function getChatSession(
    sessionId: string,
): Promise<ChatSessionResponse> {
    return ragGet(`/chats/sessions/${encodeURIComponent(sessionId)}`);
}

export function createChatSession(payload: {
    course_id: string;
    title: string;
}): Promise<ChatSessionResponse> {
    return ragJson('/chats/sessions', 'POST', payload);
}

export function deleteChatSession(sessionId: string): Promise<void> {
    return ragDelete(`/chats/sessions/${encodeURIComponent(sessionId)}`);
}

export function getChatHistory(
    sessionId: string,
): Promise<{ data: ChatMessageResponse[] }> {
    return ragGet(
        `/chats/sessions/${encodeURIComponent(sessionId)}/messages`,
    );
}

export async function openStreamChatMessage(
    sessionId: string,
    content: string,
): Promise<Response> {
    const token = getAuthToken();
    const response = await fetch(
        `${BASE_URL}/chats/sessions/${encodeURIComponent(sessionId)}/stream`,
        {
            body: JSON.stringify({ content }),
            headers: {
                Accept: 'text/event-stream',
                'Content-Type': 'application/json',
                ...(token ? { Authorization: `Bearer ${token}` } : {}),
            },
            method: 'POST',
        },
    );

    if (!response.ok) {
        throw await buildRagError(response);
    }

    return response;
}

// Auth

export async function loginUser(
    email: string,
    password: string,
): Promise<{ token: string; user: AuthUser }> {
    return ragJson('/auth/login', 'POST', { email, password });
}

export async function registerUser(
    payload: Record<string, unknown>,
): Promise<{ message?: string }> {
    return ragJson('/auth/register', 'POST', payload);
}

function setRawCookie(name: string, value: string, remember: boolean): void {
    const secure =
        typeof window !== 'undefined' &&
        window.location.protocol === 'https:';
    const maxAge = remember ? 60 * 60 * 24 * 30 : undefined;
    const parts = [
        `${name}=${encodeURIComponent(value)}`,
        'path=/',
        'SameSite=Lax',
    ];

    if (secure) {
        parts.push('Secure');
    }

    if (maxAge !== undefined) {
        parts.push(`max-age=${maxAge}`);
    }

    if (typeof document !== 'undefined') {
        document.cookie = parts.join('; ');
    }
}

export function setAuthCookies(
    token: string,
    user: AuthUser,
    remember: boolean,
): void {
    // Token cookie — dibutuhkan middleware server untuk autentikasi
    setRawCookie('sevima_raghub_auth_token', token, remember);

    // User cookie — hanya simpan role, cukup untuk pengecekan middleware server
    // Full user disimpan di localStorage agar tidak membebani request header
    setRawCookie('sevima_raghub_auth_user', JSON.stringify({ role: user.role }), remember);

    // Full user disimpan di storage lokal (tidak dikirim sebagai cookie/header)
    const storage = remember ? window.localStorage : window.sessionStorage;
    storage.setItem('sevima_raghub_auth_user', JSON.stringify(user));
}

// Admin: RAG Config

export function getRagConfig(): Promise<RagConfig> {
    return ragGet('/admin/rag/config');
}

export function getLlmConfig(): Promise<LlmConfig> {
    return ragGet('/admin/rag/config/llm');
}

export function patchLlmConfig(
    payload: Record<string, unknown>,
): Promise<LlmConfig> {
    return ragJson('/admin/rag/config/llm', 'PATCH', payload);
}

export function getVectorDbConfig(): Promise<VectorDbConfig> {
    return ragGet('/admin/rag/config/vector_db');
}

export function patchVectorDbConfig(
    payload: Record<string, unknown>,
): Promise<VectorDbConfig> {
    return ragJson('/admin/rag/config/vector_db', 'PATCH', payload);
}

export function getRetrievalConfig(): Promise<RetrievalConfig> {
    return ragGet('/admin/rag/config/retrieval');
}

export function patchRetrievalConfig(
    payload: Record<string, unknown>,
): Promise<RetrievalConfig> {
    return ragJson('/admin/rag/config/retrieval', 'PATCH', payload);
}

// Admin: API Keys

export function generateApiKey(): Promise<GeneratedApiKey> {
    return ragJson('/auth/api-keys', 'POST', {});
}

// Admin: Users

export function listAdminUsers(
    query: Record<string, string> = {},
): Promise<{ founds?: AdminUser[] }> {
    const params = new URLSearchParams(query).toString();
    const path = params ? `/user?${params}` : '/user';

    return ragGet(path);
}

export async function createAdminUser(
    payload: Record<string, unknown>,
): Promise<AdminUser> {
    const response = await ragJson<{ message: string; user: AdminUser }>(
        '/auth/register',
        'POST',
        payload,
    );
    return response.user;
}

export function updateAdminUser(
    userId: number | string,
    payload: Record<string, unknown>,
): Promise<AdminUser> {
    return ragJson(`/user/${encodeURIComponent(String(userId))}`, 'PATCH', payload);
}

export function deleteAdminUser(userId: number | string): Promise<void> {
    return ragDelete(`/user/${encodeURIComponent(String(userId))}`);
}

// Embed: internal helpers (explicit token, not from cookie)

function makeEmbedHeaders(
    token: string,
    extra: Record<string, string> = {},
): Record<string, string> {
    return {
        Accept: 'application/json',
        Authorization: `Bearer ${token}`,
        ...extra,
    };
}

async function embedGet<T>(path: string, token: string): Promise<T> {
    const response = await fetch(`${BASE_URL}${path}`, {
        headers: makeEmbedHeaders(token),
    });

    if (!response.ok) {
        throw await buildRagError(response);
    }

    return response.json() as Promise<T>;
}

async function embedJson<T>(
    path: string,
    method: string,
    body: unknown,
    token: string,
): Promise<T> {
    const response = await fetch(`${BASE_URL}${path}`, {
        body: JSON.stringify(body),
        headers: makeEmbedHeaders(token, { 'Content-Type': 'application/json' }),
        method,
    });

    if (!response.ok) {
        throw await buildRagError(response);
    }

    return response.json() as Promise<T>;
}

async function embedDelete(path: string, token: string): Promise<void> {
    const response = await fetch(`${BASE_URL}${path}`, {
        headers: makeEmbedHeaders(token),
        method: 'DELETE',
    });

    if (!response.ok) {
        throw await buildRagError(response);
    }
}

// Embed: Auth

export function loginWithEmbedApiKey(
    apiKey: string,
): Promise<{ token: string; user: AuthUser }> {
    return ragJson('/auth/login/api-key', 'POST', { api_key: apiKey });
}

// Embed: API

export function listCoursesEmbed(
    token: string,
    page = 1,
    limit = 100,
): Promise<{ data: CourseResponse[] }> {
    return embedGet(`/courses?page=${page}&limit=${limit}`, token);
}

export function listChatSessionsEmbed(
    token: string,
    courseId?: string,
    page = 1,
    limit = 50,
): Promise<{ data: ChatSessionResponse[] }> {
    const params = new URLSearchParams({
        limit: String(limit),
        page: String(page),
    });

    if (courseId) {
        params.set('course_id', courseId);
    }

    return embedGet(`/chats/sessions?${params.toString()}`, token);
}

export function getChatHistoryEmbed(
    sessionId: string,
    token: string,
): Promise<{ data: ChatMessageResponse[] }> {
    return embedGet(
        `/chats/sessions/${encodeURIComponent(sessionId)}/messages`,
        token,
    );
}

export function createChatSessionEmbed(
    payload: { course_id: string; title: string },
    token: string,
): Promise<ChatSessionResponse> {
    return embedJson('/chats/sessions', 'POST', payload, token);
}

export function deleteChatSessionEmbed(
    sessionId: string,
    token: string,
): Promise<void> {
    return embedDelete(
        `/chats/sessions/${encodeURIComponent(sessionId)}`,
        token,
    );
}

export function sendRestChatMessage(
    sessionId: string,
    content: string,
    token: string,
): Promise<ChatMessageResponse> {
    return embedJson(
        `/chats/sessions/${encodeURIComponent(sessionId)}/messages`,
        'POST',
        { content },
        token,
    );
}

export async function queryAiDirect(
    courseId: string,
    prompt: string,
    token: string,
): Promise<ChatMessageResponse> {
    type DirectResponse = {
        message_id: string;
        role?: string;
        content: string;
        sources?: DocumentSource[];
        created_at: string;
    };

    const data = await embedJson<DirectResponse>(
        '/ai/query',
        'POST',
        { course_id: courseId, prompt },
        token,
    );

    return {
        content: data.content,
        created_at: data.created_at,
        role: data.role ?? 'assistant',
        sources: data.sources ?? [],
        uuid_id: data.message_id,
    };
}