import { API_DEFAULTS } from "../config/constants";

const BASE_URL = import.meta.env.VITE_ORCHESTRATION_URL ?? '';

// ── Sessions ────────────────────────────────────────────────

export async function fetchSessions(limit = API_DEFAULTS.SESSIONS_LIMIT, offset = API_DEFAULTS.OFFSET) {
  const res = await fetch(`${BASE_URL}/sessions?limit=${limit}&offset=${offset}`);
  if (!res.ok) throw new Error(`Failed to fetch sessions: ${res.status}`);
  return res.json();
}

export async function fetchSessionHistory(sessionId, limit = API_DEFAULTS.HISTORY_LIMIT, offset = API_DEFAULTS.OFFSET) {
  const res = await fetch(`${BASE_URL}/sessions/${sessionId}/history?limit=${limit}&offset=${offset}`);
  if (!res.ok) throw new Error(`Failed to fetch history: ${res.status}`);
  return res.json();
}

// ── Chat ────────────────────────────────────────────────────

export async function sendMessage(sessionId, message, model) {
  const res = await fetch(`${BASE_URL}/chat`, {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ sessionId, message, model }),
  });
  if (!res.ok) throw new Error(`Chat request failed: ${res.status}`);
  return res.json();
}

// onChunk(text) called for each token
// onDone({ model, tokenCount }) called when stream closes
// returns an abort function — call it to cancel mid-stream
/*
export function streamMessage(sessionId, message, model, { onChunk, onDone, onError }) {
  const controller = new AbortController();

  (async () => {
    try {
      const res = await fetch(`${BASE_URL}/chat/stream`, {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ sessionId, message, model }),
        signal: controller.signal,
      });

      if (!res.ok) throw new Error(`Stream request failed: ${res.status}`);

      const reader = res.body.getReader();
      const decoder = new TextDecoder();
      let buffer = '';

      while (true) {
        const { done, value } = await reader.read();
        if (done) break;

        // Append to buffer and split on double newline (SSE event delimiter)
        buffer += decoder.decode(value, { stream: true });
        const events = buffer.split('\n\n');
        buffer = events.pop(); // last item may be incomplete — keep in buffer

        for (const event of events) {
          const line = event.trim();
          if (!line.startsWith('data: ')) continue;

          const raw = line.slice(6);
          try {
            const data = JSON.parse(raw);
            if (data.text) onChunk(data.text);
            if (data.done) onDone({ model: data.model ?? model, tokenCount: data.tokenCount ?? 0 });
            if (data.error) onError(new Error(data.error));
          } catch {
            // malformed JSON — skip
          }
        }
      }
    } catch (err) {
      if (err.name !== 'AbortError') onError(err);
    }
  })();

  return () => controller.abort();
}
*/
export function streamMessage(sessionId, message, model, { onChunk, onDone, onError }) {
  const controller = new AbortController();

  (async () => {
    try {
      const res = await fetch(`${BASE_URL}/chat/stream`, {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ sessionId, message, model }),
        signal: controller.signal,
      });

      if (!res.ok) throw new Error(`Stream request failed: ${res.status}`);

      const reader = res.body.getReader();
      const decoder = new TextDecoder();
      let buffer = '';

      while (true) {
        const { done, value } = await reader.read();
        if (done) break;

        buffer += decoder.decode(value, { stream: true });

        const events = buffer.split('\n\n');
        buffer = events.pop() || '';

        for (const event of events) {
          const lines = event.split('\n');
          const dataLines = lines
            .filter(line => line.startsWith('data: '))
            .map(line => line.slice(6));

          if (dataLines.length === 0) continue;

          const raw = dataLines.join('\n').trim();
          if (raw === '[DONE]') continue;

          try {
            const data = JSON.parse(raw);

            if (data.text) onChunk(data.text);
            if (data.done) onDone({ model: data.model ?? model, tokenCount: data.tokenCount ?? 0 });
            if (data.error) onError(new Error(data.error));
          } catch (err) {
            console.error('[chat-client] Failed to parse SSE event:', raw, err);
          }
        }
      }
    } catch (err) {
      if (err.name !== 'AbortError') onError(err);
    }
  })();

  return () => controller.abort();
}
export async function fetchModels() {
  const res = await fetch(`${BASE_URL}/models`);
  if(!res.ok) throw new Error(`Failted to fetch models: ${res.status}`);
  return res.json();
}
/*
export async function renameSession(sessionId, name) {
    const res = await fetch(`${BASE_URL}/sessions/${sessionId}`, {
        method: 'PATCH',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ name }),
    });
    if (!res.ok) throw new Error(`Failed to rename session: ${res.status}`);
    return res.json();
}
*/
export async function updateSession(sessionId, { name, projectId } = {}) {
  const res = await fetch(`${BASE_URL}/sessions/${sessionId}`, {
    method: 'PATCH',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ name, projectId }),
  });
  if (!res.ok) throw new Error(`Failed to update session: ${res.status}`);
  return res.json();
}

export async function renameSession(sessionId, name) {
  return updateSession(sessionId, {name})
}

export async function deleteSession(sessionId) {
    const res = await fetch(`${BASE_URL}/sessions/${sessionId}`, {
        method: 'DELETE',
    });
    if (!res.ok) throw new Error(`Failed to delete session: ${res.status}`);
}

export async function fetchProjects() {
  const res = await fetch(`${BASE_URL}/projects`);
  if (!res.ok) throw new Error(`Failed to fetch projects: ${res.status}`);
  return res.json();
}

export async function createProject({ name, description, colour, icon }) {
  const res = await fetch(`${BASE_URL}/projects`, {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ name, description, colour, icon }),
  });
  if (!res.ok) throw new Error(`Failed to create project: ${res.status}`);
  return res.json();
}

export async function updateProject(id, { name, description, colour, icon }) {
  const res = await fetch(`${BASE_URL}/projects/${id}`, {
    method: 'PATCH',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ name, description, colour, icon }),
  });
  if (!res.ok) throw new Error(`Failed to update project: ${res.status}`);
  return res.json();
}

export async function deleteProject(id) {
  const res = await fetch(`${BASE_URL}/projects/${id}`, { method: 'DELETE' });
  if (!res.ok) throw new Error(`Failed to delete project: ${res.status}`);
}

export async function updateSessionProject(sessionId, projectId) {
  const res = await fetch(`${BASE_URL}/sessions/${sessionId}`, {
    method: 'PATCH',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ projectId }),
  });
  if (!res.ok) throw new Error(`Failed to update session project: ${res.status}`);
  return res.json();
}