import { generateObject, generateText, type LanguageModel } from "ai";
import type { z } from "zod";
import { extractJsonFromText } from "./coerce-research-map";
import {
  getOpenCodeGenerationSettings,
  prefersOpenCodeTextFirst,
} from "./opencode-go-settings";

export interface GenerateStructuredObjectOptions<S extends z.ZodTypeAny> {
  model: LanguageModel;
  schema: S;
  system?: string;
  prompt: string;
  provider: string;
  modelId: string;
  jsonPromptSuffix?: string;
  normalize?: (value: unknown) => unknown;
}

export async function generateStructuredObject<S extends z.ZodTypeAny>(
  options: GenerateStructuredObjectOptions<S>
): Promise<z.infer<S>> {
  const settings = getOpenCodeGenerationSettings(options.provider, options.modelId);
  const preferText = prefersOpenCodeTextFirst(options.provider, options.modelId);
  const jsonSuffix =
    options.jsonPromptSuffix ?? "\n\n只回傳 JSON，不要 markdown 或額外說明。\n\n強制：所有文字欄位必須使用繁體中文（台灣用語），絕對禁止簡體字。";

  async function viaObject() {
    const { object } = await generateObject({
      model: options.model,
      schema: options.schema,
      system: `${options.system ?? ""}\n\n強制：所有文字欄位必須使用繁體中文（台灣用語），絕對禁止簡體字。`,
      prompt: options.prompt,
      ...settings,
    });
    return options.schema.parse(options.normalize ? options.normalize(object) : object);
  }

  async function viaText(extra = "") {
    const { text } = await generateText({
      model: options.model,
      system: options.system,
      prompt: `${options.prompt}${jsonSuffix}${extra}`,
      ...settings,
    });
    let parsed = extractJsonFromText(text);
    if (Array.isArray(parsed) && parsed.length > 0) {
      parsed = parsed[0];
    }
    return options.schema.parse(options.normalize ? options.normalize(parsed) : parsed);
  }

  const attempts: Array<() => Promise<z.infer<S>>> = preferText
    ? [
        () => viaText(),
        () => viaObject(),
        () => viaText("\n\n上次格式不完整，請務必回傳合法 JSON。"),
      ]
    : [
        () => viaObject(),
        () => viaText(),
        () => viaText("\n\n上次格式不完整，請務必回傳合法 JSON。"),
      ];

  let lastError: unknown;
  for (const attempt of attempts) {
    try {
      return await attempt();
    } catch (error) {
      lastError = error;
    }
  }

  throw lastError instanceof Error ? lastError : new Error("結構化 AI 回傳失敗");
}