import crypto from "crypto";
import { BaseExecutor } from "./base.js";
import { PROVIDERS } from "../config/providers.js";
import { getThinkingLevels } from "../providers/thinkingLevels.js";
import { injectReasoningContent } from "../utils/reasoningContentInjector.js";
import { resolveSessionId } from "../utils/sessionManager.js";

const OPENCODE_UA = "opencode";
// Models served by /zen/v1/responses; every other model stays on /chat/completions.
const RESPONSES_MODELS = new Set(["muse-spark-1.2-contributor-free"]);

function generateRequestId() {
  return `msg_${crypto.randomUUID().replace(/-/g, "")}`;
}

function generateSessionId() {
  return `ses_${crypto.randomUUID().replace(/-/g, "")}`;
}

// Strip the thinking suffix "model(level)" so registry lookups hit the base id.
function baseModelId(model) {
  return String(model || "").replace(/\([^()]+\)\s*$/, "").trim();
}

function isResponsesModel(model) {
  return RESPONSES_MODELS.has(baseModelId(model));
}

function resolveOpencodeSession(body, credentials) {
  const headers = credentials?.rawHeaders || {};
  return resolveSessionId({
    headers,
    body,
    connectionId: credentials?.connectionId,
    scope: "opencode",
    generate: generateSessionId,
  });
}

function normalizeOpencodeReasoning(model, body) {
  const current = body.reasoning;
  const currentReasoning = current && typeof current === "object" && !Array.isArray(current)
    ? current
    : null;
  const requestedEffort = typeof body.reasoning_effort === "string"
    ? body.reasoning_effort
    : currentReasoning?.effort;
  if (typeof requestedEffort !== "string") return;

  const cleanModel = baseModelId(model || body.model);
  const supportedLevels = getThinkingLevels("opencode", cleanModel);
  let effort = requestedEffort.toLowerCase().trim();
  if ((effort === "max" || effort === "ultra") && supportedLevels?.length && !supportedLevels.includes(effort)) {
    if (effort === "ultra" && supportedLevels.includes("max")) effort = "max";
    else if (supportedLevels.includes("xhigh")) effort = "xhigh";
  }

  body.reasoning = { ...currentReasoning, effort };
  if (!body.reasoning.summary) body.reasoning.summary = "auto";
  delete body.reasoning_effort;
}

export class OpenCodeExecutor extends BaseExecutor {
  constructor() {
    super("opencode", PROVIDERS.opencode);
    this._currentSessionId = null;
  }

  transformRequest(model, body, stream, credentials) {
    this._currentSessionId = resolveOpencodeSession(body, credentials);
    if (isResponsesModel(model)) {
      // Responses API names the output cap max_output_tokens and takes thinking
      // as reasoning:{effort,summary} — normalize the Chat fields at this boundary.
      if (body.max_output_tokens === undefined) {
        if (body.max_completion_tokens !== undefined) body.max_output_tokens = body.max_completion_tokens;
        else if (body.max_tokens !== undefined) body.max_output_tokens = body.max_tokens;
      }
      delete body.max_tokens;
      delete body.max_completion_tokens;
      normalizeOpencodeReasoning(model, body);
    }
    return injectReasoningContent({ provider: this.provider, model, body });
  }

  buildUrl(model) {
    const base = this.config.baseUrl;
    return isResponsesModel(model)
      ? `${base}/zen/v1/responses`
      : `${base}/zen/v1/chat/completions`;
  }

  buildHeaders(credentials, stream = true) {
    const raw = credentials?.rawHeaders || {};
    const lower = {};
    for (const [k, v] of Object.entries(raw)) lower[k.toLowerCase()] = v;

    const downstreamUa = lower["user-agent"] || "";
    const isOpencodeDownstream = downstreamUa.toLowerCase().includes("opencode");

    return {
      "Content-Type": "application/json",
      "Authorization": "Bearer public",
      "User-Agent": isOpencodeDownstream ? downstreamUa : OPENCODE_UA,
      "x-opencode-client": lower["x-opencode-client"] || "desktop",
      "x-opencode-session": lower["x-opencode-session"] || this._currentSessionId || generateSessionId(),
      "x-opencode-request": lower["x-opencode-request"] || generateRequestId(),
      "x-opencode-project": lower["x-opencode-project"] || "global",
      "Accept": stream ? "text/event-stream" : "*/*",
    };
  }
}