/**
 * API client for the FastAPI backend (Ops-Core).
 * Base URL is read from NEXT_PUBLIC_API_BASE (default http://localhost:8000).
 */

const getBase = (): string => {
  if (typeof window !== "undefined") {
    return process.env.NEXT_PUBLIC_API_BASE ?? "http://localhost:8000";
  }
  return process.env.NEXT_PUBLIC_API_BASE ?? "http://localhost:8000";
};

export const apiBase = getBase;

// --------------- Types (mirror FastAPI schemas) ---------------

export interface CustomerRead {
  id: number;
  name: string;
  contact_info: string | null;
  created_at: string;
}

export interface CustomerCreate {
  name: string;
  contact_info?: string | null;
}

export interface CustomerUpdate {
  name?: string;
  contact_info?: string | null;
}

export interface RequirementAnalyzeRequest {
  customer_id: number;
  raw_text: string;
}

export interface RequirementAnalyzeResponse {
  project_id: number;
  ai_solution_md: string;
  ai_solution_json: Record<string, unknown>;
}

export interface QuoteGenerateResponse {
  quote_id: number;
  project_id: number;
  total_amount: number;
  excel_path: string;
  pdf_path: string;
}

export interface ContractGenerateRequest {
  delivery_date: string;
  extra_placeholders?: Record<string, string>;
}

export interface ContractGenerateResponse {
  project_id: number;
  contract_path: string;
}

export interface FinanceSyncResult {
  id: number;
  month: string;
  type: string;
  file_name: string;
  file_path: string;
}

export interface FinanceSyncResponse {
  items: FinanceSyncResult[];
}

export interface ProjectRead {
  id: number;
  customer_id: number;
  raw_requirement: string;
  ai_solution_md: string | null;
  status: string;
  created_at: string;
  customer?: CustomerRead;
  quotes?: { id: number; total_amount: string; file_path: string }[];
}

export interface ProjectUpdate {
  ai_solution_md?: string | null;
  status?: string;
}

// --------------- Request helper ---------------

async function request<T>(
  path: string,
  options: RequestInit & { params?: Record<string, string> } = {}
): Promise<T> {
  const { params, ...init } = options;
  const base = apiBase();
  let url = `${base}${path}`;
  if (params && Object.keys(params).length > 0) {
    const search = new URLSearchParams(params).toString();
    url += (path.includes("?") ? "&" : "?") + search;
  }

  const res = await fetch(url, {
    ...init,
    headers: {
      "Content-Type": "application/json",
      ...init.headers,
    },
  });

  if (!res.ok) {
    const text = await res.text();
    let detail = text;
    try {
      const j = JSON.parse(text);
      detail = j.detail ?? text;
    } catch {
      // keep text
    }
    throw new Error(detail);
  }

  const contentType = res.headers.get("content-type");
  if (contentType?.includes("application/json")) {
    return res.json() as Promise<T>;
  }
  return undefined as T;
}

/** Download a file from the backend and return a Blob (for Excel/PDF/Zip). */
export async function downloadBlob(path: string): Promise<Blob> {
  const base = apiBase();
  const url = path.startsWith("http") ? path : `${base}${path.startsWith("/") ? "" : "/"}${path}`;
  const res = await fetch(url, { credentials: "include" });
  if (!res.ok) throw new Error(`Download failed: ${res.status}`);
  return res.blob();
}

/**
 * Trigger download in the browser (Excel, PDF, or Zip).
 * path: backend-returned path e.g. "data/quotes/quote_project_1.xlsx" -> we request /data/quotes/quote_project_1.xlsx
 */
export function downloadFile(path: string, filename: string): void {
  const base = apiBase();
  const normalized = path.startsWith("/") ? path : `/${path}`;
  const url = `${base}${normalized}`;
  const a = document.createElement("a");
  a.href = url;
  a.download = filename;
  a.rel = "noopener noreferrer";
  a.target = "_blank";
  document.body.appendChild(a);
  a.click();
  document.body.removeChild(a);
}

/** Same as downloadFile but using fetch + Blob for consistent CORS and filename control. */
export async function downloadFileAsBlob(
  path: string,
  filename: string,
  mime?: string
): Promise<void> {
  const blob = await downloadBlob(path);
  const url = URL.createObjectURL(blob);
  const a = document.createElement("a");
  a.href = url;
  a.download = filename;
  document.body.appendChild(a);
  a.click();
  document.body.removeChild(a);
  URL.revokeObjectURL(url);
}

// --------------- Customers ---------------

export const customersApi = {
  list: () => request<CustomerRead[]>("/customers/"),
  get: (id: number) => request<CustomerRead>(`/customers/${id}`),
  create: (body: CustomerCreate) =>
    request<CustomerRead>("/customers/", {
      method: "POST",
      body: JSON.stringify(body),
    }),
  update: (id: number, body: CustomerUpdate) =>
    request<CustomerRead>(`/customers/${id}`, {
      method: "PUT",
      body: JSON.stringify(body),
    }),
  delete: (id: number) =>
    request<void>(`/customers/${id}`, { method: "DELETE" }),
};

// --------------- Projects ---------------

export const projectsApi = {
  analyze: (body: RequirementAnalyzeRequest) =>
    request<RequirementAnalyzeResponse>("/projects/analyze", {
      method: "POST",
      body: JSON.stringify(body),
    }),

  update: (projectId: number, body: ProjectUpdate) =>
    request<ProjectRead>(`/projects/${projectId}`, {
      method: "PATCH",
      body: JSON.stringify(body),
    }),

  generateQuote: (projectId: number) =>
    request<QuoteGenerateResponse>(`/projects/${projectId}/generate_quote`, {
      method: "POST",
    }),

  generateContract: (projectId: number, body: ContractGenerateRequest) =>
    request<ContractGenerateResponse>(
      `/projects/${projectId}/generate_contract`,
      {
        method: "POST",
        body: JSON.stringify(body),
      }
    ),
};

export async function listProjects(): Promise<ProjectRead[]> {
  return request<ProjectRead[]>("/projects/");
}

export async function getProject(projectId: number): Promise<ProjectRead> {
  return request<ProjectRead>(`/projects/${projectId}`);
}

// --------------- Finance ---------------

export const financeApi = {
  sync: () =>
    request<FinanceSyncResponse>("/finance/sync", { method: "POST" }),

  /** Returns the URL to download the zip (or use downloadFile with the path). */
  getDownloadUrl: (month: string) => `${apiBase()}/finance/download/${month}`,

  /** Download monthly zip as blob and trigger save. */
  downloadMonth: async (month: string): Promise<void> => {
    const path = `/finance/download/${month}`;
    await downloadFileAsBlob(path, `finance_${month}.zip`, "application/zip");
  },
};