import {
  calculateBazi,
  formatBaziForPrompt,
} from "@/lib/calc/bazi";
import {
  formatLiuyaoTimingForPrompt,
  formatTimingForPrompt,
  getTimingInfoWithLongitude,
} from "@/lib/calc/timing";
import {
  extractChangeDetails,
  extractZhangMingRen,
  readGuaMarkdown,
} from "@/lib/content/zhouyi";
import {
  BAZI_SYSTEM_PROMPT,
  COMBINED_SYSTEM_PROMPT,
  LIUYAO_SYSTEM_PROMPT,
} from "@/lib/prompts";
import type { AiRequestBody } from "@/lib/ai/types";

export async function buildAiMessages(
  body: AiRequestBody,
): Promise<{ system: string; user: string }> {
  switch (body.mode) {
    case "liuyao": {
      const input = body.payload;
      const { timing, trueSolarTime } = getTimingInfoWithLongitude(
        input.calcDate,
        input.calcTime,
        input.longitude,
      );
      const timingText = formatLiuyaoTimingForPrompt(
        timing,
        trueSolarTime,
        input.locationName,
        input.longitude,
      );

      let guaDetailText = "";
      try {
        const guaDetail = await readGuaMarkdown(input.guaMark);
        const explain = extractZhangMingRen(guaDetail) ?? "";
        const changeList = extractChangeDetails(
          guaDetail,
          input.guaChange,
          input.guaTitle,
        );
        guaDetailText = [explain, changeList.join("\n")]
          .filter(Boolean)
          .join("\n");
      } catch {
        guaDetailText = "";
      }

      return {
        system: LIUYAO_SYSTEM_PROMPT,
        user: `${timingText}

【卦象】
${input.guaTitle} ${input.guaResult} ${input.guaChange}

【问事】
${input.question}

${guaDetailText}`,
      };
    }
    case "bazi": {
      const { input, question, birthPlaceName } = body.payload;
      const chart = calculateBazi(input);
      const chartText = formatBaziForPrompt(chart);
      return {
        system: BAZI_SYSTEM_PROMPT,
        user: `【出生时空】
出生地：${birthPlaceName}

【排盘信息】
${chartText}

【问事】
${question}`,
      };
    }
    case "combined": {
      const input = body.payload;
      const chart = calculateBazi(input.birth);
      const chartText = formatBaziForPrompt(chart);
      const { timing, trueSolarTime } = getTimingInfoWithLongitude(
        input.calcDate,
        input.calcTime,
        input.currentLongitude,
      );
      const timingText = [
        formatTimingForPrompt(
          timing,
          input.currentPlaceName,
          input.currentLongitude,
        ),
        `真太阳时：${trueSolarTime}`,
      ].join("\n");

      let hexagramText = "";
      if (input.hexagram) {
        const { guaMark, guaTitle, guaResult, guaChange } = input.hexagram;
        try {
          const guaDetail = await readGuaMarkdown(guaMark);
          const explain = extractZhangMingRen(guaDetail) ?? "";
          const changeList = extractChangeDetails(
            guaDetail,
            guaChange,
            guaTitle,
          );
          hexagramText = [
            "",
            "【卦象 · 可选六爻】",
            `${guaTitle} ${guaResult} ${guaChange}`,
            explain,
            changeList.join("\n"),
          ].join("\n");
        } catch {
          hexagramText = [
            "",
            "【卦象 · 可选六爻】",
            `${input.hexagram.guaTitle} ${input.hexagram.guaResult} ${input.hexagram.guaChange}`,
          ].join("\n");
        }
      }

      return {
        system: COMBINED_SYSTEM_PROMPT,
        user: `【人和 · 八字排盘】
出生地：${input.birthPlaceName}
${chartText}

${timingText}
${hexagramText}

【问事】
${input.question}`,
      };
    }
  }
  throw new Error("未知 AI 模式");
}