const API_URL = process.env.NEXT_PUBLIC_API_URL ?? "https://soc-backend.azurewebsites.net";

// ── Conversations ────────────────────────────────────────────────────────────

export interface ConversationSummary {
  id: string;
  title: string;
  created_at: string;
  updated_at: string;
}

export interface ApiMessage {
  id: string;
  role: "human" | "ai";
  content: string;
  created_at: string;
}

export interface ConversationDetail extends ConversationSummary {
  messages: ApiMessage[];
}

export async function fetchConversations(): Promise<ConversationSummary[]> {
  const res = await fetch(`${API_URL}/api/conversations`);
  if (!res.ok) throw new Error("Failed to fetch conversations");
  return res.json();
}

export async function fetchConversation(id: string): Promise<ConversationDetail> {
  const res = await fetch(`${API_URL}/api/conversations/${id}`);
  if (!res.ok) throw new Error("Failed to fetch conversation");
  return res.json();
}

export async function createConversation(title?: string): Promise<ConversationSummary> {
  const res = await fetch(`${API_URL}/api/conversations`, {
    method: "POST",
    headers: { "Content-Type": "application/json" },
    body: JSON.stringify({ title: title ?? "New conversation" }),
  });
  if (!res.ok) throw new Error("Failed to create conversation");
  return res.json();
}

export async function deleteConversation(id: string): Promise<void> {
  const res = await fetch(`${API_URL}/api/conversations/${id}`, { method: "DELETE" });
  if (!res.ok) throw new Error("Failed to delete conversation");
}

// ── Tickets ──────────────────────────────────────────────────────────────────

export interface TicketData {
  id: string;
  title: string;
  status: "pending" | "processing" | "resolved";
  priority: "P0" | "P1" | "P2" | "P3";
  createdAt: string;
}

export async function fetchTickets(page = 1, pageSize = 20): Promise<TicketData[]> {
  const res = await fetch(`${API_URL}/api/tickets?page=${page}&page_size=${pageSize}`);
  if (!res.ok) throw new Error("Failed to fetch tickets");
  return res.json();
}

export interface TicketSummaryData {
  total: number;
  by_status: { pending: number; processing: number; resolved: number };
  by_priority: { P0: number; P1: number; P2: number; P3: number };
}

export async function fetchTicketSummary(): Promise<TicketSummaryData> {
  const res = await fetch(`${API_URL}/api/tickets/summary`);
  if (!res.ok) throw new Error("Failed to fetch ticket summary");
  return res.json();
}

// ── Attachments ─────────────────────────────────────────────────────────────

export interface AttachmentData {
  id: string;
  filename: string;
  content_type: string;
  blob_url: string;
  size_bytes: number;
  created_at: string;
}

export async function uploadAttachment(
  file: File,
  conversationId?: string,
): Promise<AttachmentData> {
  const form = new FormData();
  form.append("data", file);

  const params = conversationId ? `?conversation_id=${conversationId}` : "";
  const res = await fetch(`${API_URL}/api/attachments/upload${params}`, {
    method: "POST",
    body: form,
  });
  if (!res.ok) {
    const text = await res.text().catch(() => "Unknown error");
    throw new Error(`Upload failed (${res.status}): ${text}`);
  }
  return res.json();
}

export function getAttachmentDownloadUrl(attachmentId: string): string {
  return `${API_URL}/api/attachments/${attachmentId}/download`;
}

// ── SSE Chat Stream ──────────────────────────────────────────────────────────

export interface ChatStreamEvent {
  type: "token" | "status" | "tool_start" | "tool_end" | "tool_error" | "done" | "error";
  // token
  content?: string;
  // status
  stage?: string;
  message?: string;
  // tool_start / tool_end / tool_error
  tool?: string;
  title?: string;
  input_summary?: string;
  output_summary?: string;
  error_summary?: string;
  status?: "success" | "error";
  duration_ms?: number;
  ts?: number;
}

export interface TraceItem {
  id: string;
  type: "status" | "tool_start" | "tool_end" | "tool_error";
  tool?: string;
  title: string;
  message?: string;
  inputSummary?: string;
  outputSummary?: string;
  errorSummary?: string;
  itemStatus: "running" | "success" | "error" | "info";
  durationMs?: number;
  startTs: number;
}

export function streamChat(
  message: string,
  conversationId: string,
  tools: string[],
  model: "flash" | "pro",
  onEvent: (event: ChatStreamEvent) => void,
  onError: (error: Error) => void,
  onDone: () => void,
): AbortController {
  const controller = new AbortController();

  fetch(`${API_URL}/api/chat/stream`, {
    method: "POST",
    headers: { "Content-Type": "application/json" },
    body: JSON.stringify({ message, conversation_id: conversationId, tools, model }),
    signal: controller.signal,
  })
    .then(async (res) => {
      if (!res.ok) {
        const text = await res.text().catch(() => "Unknown error");
        throw new Error(`Chat stream failed (${res.status}): ${text}`);
      }

      const reader = res.body?.getReader();
      if (!reader) throw new Error("No response body");

      const decoder = new TextDecoder();
      let buffer = "";

      while (true) {
        const { done, value } = await reader.read();
        if (done) {
          // Process any remaining data in buffer (last line may lack trailing newline)
          if (buffer.trim()) {
            const trimmed = buffer.trim();
            if (trimmed.startsWith("data: ")) {
              const json = trimmed.slice(6);
              if (json) {
                try {
                  const event: ChatStreamEvent = JSON.parse(json);
                  onEvent(event);
                } catch {
                  // skip malformed
                }
              }
            }
          }
          break;
        }

        buffer += decoder.decode(value, { stream: true });
        const lines = buffer.split("\n");
        buffer = lines.pop() ?? "";

        for (const line of lines) {
          const trimmed = line.trim();
          if (!trimmed.startsWith("data: ")) continue;
          const json = trimmed.slice(6);
          if (!json) continue;
          try {
            const event: ChatStreamEvent = JSON.parse(json);
            onEvent(event);
            if (event.type === "done") {
              onDone();
              return;
            }
          } catch {
            // skip malformed events
          }
        }
      }
      onDone();
    })
    .catch((err) => {
      if (err.name !== "AbortError") {
        onError(err);
      }
    });

  return controller;
}