"use client";

import { useState } from "react";
import { readStreamableValue } from "ai/rsc";
import { BrainCircuit } from "lucide-react";
import { Button } from "@/components/ui/button";
import { Textarea } from "@/components/ui/textarea";
import ResultAI from "@/components/result-ai";
import BaziChartDisplay from "@/components/modes/bazi-chart";
import DateTimePicker, { nowDateString } from "@/components/shared/datetime-picker";
import RegionSelect, {
  useRegionLocation,
} from "@/components/shared/region-select";
import { calculateBazi, type BaziChart } from "@/lib/calc/bazi";
import { getBaziAnswer } from "@/app/actions/bazi";
import { ERROR_PREFIX } from "@/lib/constant";

export default function BaziForm() {
  const [date, setDate] = useState(nowDateString());
  const [time, setTime] = useState("12:00");
  const [unknownHour, setUnknownHour] = useState(false);
  const [gender, setGender] = useState<"male" | "female">("male");
  const [provinceCode, setProvinceCode] = useState("");
  const [cityCode, setCityCode] = useState("");
  const [question, setQuestion] = useState("");
  const [chart, setChart] = useState<BaziChart | null>(null);
  const [completion, setCompletion] = useState("");
  const [error, setError] = useState("");
  const [isLoading, setIsLoading] = useState(false);
  const [showAi, setShowAi] = useState(false);

  const location = useRegionLocation(provinceCode, cityCode);

  function buildInput() {
    if (!location) {
      return null;
    }
    return {
      date,
      time: unknownHour ? "12:00" : time,
      gender,
      longitude: location.longitude,
      unknownHour,
    };
  }

  function handleCalculate() {
    const input = buildInput();
    if (!input) {
      setError("请选择出生地域");
      return;
    }
    if (!question.trim()) {
      setError("请输入问事");
      return;
    }
    setError("");
    setChart(calculateBazi(input));
    setShowAi(false);
    setCompletion("");
  }

  async function handleAnalyze() {
    const input = buildInput();
    if (!input || !chart) {
      return;
    }
    setError("");
    setCompletion("");
    setIsLoading(true);
    setShowAi(true);
    try {
      const { data, error: apiError } = await getBaziAnswer(
        input,
        question,
        location!.name,
      );
      if (apiError) {
        setError(apiError);
        return;
      }
      if (data) {
        let ret = "";
        for await (const delta of readStreamableValue(data)) {
          if (typeof delta === "string" && delta.startsWith(ERROR_PREFIX)) {
            setError(delta.slice(ERROR_PREFIX.length));
            return;
          }
          ret += delta ?? "";
          setCompletion(ret);
        }
      }
    } catch (err) {
      setError(err instanceof Error ? err.message : String(err));
    } finally {
      setIsLoading(false);
    }
  }

  return (
    <div className="flex flex-1 flex-col gap-4 px-4 py-6">
      <div className="mx-auto w-full max-w-lg space-y-4">
        <DateTimePicker
          label="出生日期 / 时间"
          date={date}
          time={time}
          timeDisabled={unknownHour}
          onDateChange={setDate}
          onTimeChange={setTime}
        />
        <label className="flex items-center gap-2 text-xs text-muted-foreground">
          <input
            type="checkbox"
            checked={unknownHour}
            onChange={(e) => setUnknownHour(e.target.checked)}
          />
          时辰不详
        </label>

        <div className="space-y-1">
          <label className="text-sm font-medium">性别</label>
          <div className="flex gap-4">
            {(["male", "female"] as const).map((g) => (
              <label key={g} className="flex items-center gap-2 text-sm">
                <input
                  type="radio"
                  name="gender"
                  checked={gender === g}
                  onChange={() => setGender(g)}
                />
                {g === "male" ? "男" : "女"}
              </label>
            ))}
          </div>
        </div>

        <RegionSelect
          label="出生地域"
          provinceCode={provinceCode}
          cityCode={cityCode}
          onProvinceChange={setProvinceCode}
          onCityChange={setCityCode}
        />

        <div className="space-y-1">
          <label className="text-sm font-medium">问事</label>
          <Textarea
            placeholder="事业、婚姻、健康等..."
            value={question}
            onChange={(e) => setQuestion(e.target.value)}
            rows={3}
          />
        </div>

        {error && !showAi && (
          <p className="text-sm text-destructive">{error}</p>
        )}

        <Button onClick={handleCalculate} className="w-full">
          排盘
        </Button>
      </div>

      {chart && (
        <div className="mx-auto w-full max-w-lg space-y-4">
          <BaziChartDisplay chart={chart} />
          {!showAi && (
            <Button onClick={handleAnalyze} className="w-full">
              <BrainCircuit size={16} className="mr-1" />
              测算
            </Button>
          )}
        </div>
      )}

      {showAi && (
        <div className="mx-auto h-96 w-full max-w-lg flex-1">
          <ResultAI
            completion={completion}
            isLoading={isLoading}
            onCompletion={handleAnalyze}
            error={error}
          />
        </div>
      )}
    </div>
  );
}