import { useEffect, useRef, useState } from "react";
import { apiGet, apiUpload } from "../../lib/api";
import { ModelSelector } from "../ModelSelector";

interface ParserOption {
  id: string;
  name: string;
  description: string;
}

interface FileUploadPanelProps {
  sessionId: number;
  parsedData: Record<string, unknown>;
  onParsedDataUpdate: (dataType: string, data: unknown) => void;
  onGoToStep2: () => void;
}

interface UploadZone {
  type: "questions" | "answers";
  label: string;
  description: string;
  placeholder: string;
  icon: string;
}

const zones: UploadZone[] = [
  {
    type: "questions",
    label: "考試題目",
    description: "上傳考試試卷（任意格式）",
    placeholder: "例如：國中三年級數學期中考，共 20 題選擇題和 5 題計算題",
    icon: "📝",
  },
  {
    type: "answers",
    label: "答案",
    description: "上傳作答一覽表（PDF / CSV / 圖片）",
    placeholder:
      "例如：A 卷的考生作答一覽表（CSV 第 1 列為題號標題，第 2 列為標準答案，第 3 列起為學生）",
    icon: "✅",
  },
];

export function FileUploadPanel({
  sessionId,
  parsedData,
  onParsedDataUpdate,
  onGoToStep2,
}: FileUploadPanelProps) {
  const [files, setFiles] = useState<Record<string, File[]>>({
    questions: [],
    answers: [],
  });
  const [descriptions, setDescriptions] = useState<Record<string, string>>({
    questions: "",
    answers: "",
  });
  const [analyzing, setAnalyzing] = useState<Record<string, boolean>>({});
  const [errors, setErrors] = useState<Record<string, string>>({});
  const [model, setModel] = useState("gpt-5.4");
  const [parsers, setParsers] = useState<ParserOption[]>([]);
  const [parserByZone, setParserByZone] = useState<Record<string, string>>({
    questions: "auto",
    answers: "auto",
  });
  const fileInputRefs = useRef<Record<string, HTMLInputElement | null>>({});

  useEffect(() => {
    apiGet<{ parsers: ParserOption[] }>("/api/parsers")
      .then((res) => setParsers(res.parsers))
      .catch(() => {});
  }, []);

  const handleFileSelect = (type: string, selected: FileList | null) => {
    if (!selected) return;
    setFiles((prev) => ({ ...prev, [type]: Array.from(selected) }));
    setErrors((prev) => ({ ...prev, [type]: "" }));
  };

  const handleDrop = (type: string, e: React.DragEvent) => {
    e.preventDefault();
    handleFileSelect(type, e.dataTransfer.files);
  };

  const handleAnalyze = async (type: string) => {
    const typeFiles = files[type];
    if (!typeFiles.length) return;

    setAnalyzing((prev) => ({ ...prev, [type]: true }));
    setErrors((prev) => ({ ...prev, [type]: "" }));

    try {
      const formData = new FormData();
      formData.append("data_type", type);
      formData.append("description", descriptions[type] || "");
      formData.append("model", model);
      formData.append("parser", parserByZone[type] || "auto");
      for (const f of typeFiles) {
        formData.append("files", f);
      }
      const res = await apiUpload<{ data: unknown }>(`/api/sessions/${sessionId}/upload`, formData);
      if (type === "answers") {
        const data = res.data as {
          student_answers?: unknown;
          teacher_answers?: unknown;
        };
        if (data.student_answers) onParsedDataUpdate("student_answers", data.student_answers);
        if (data.teacher_answers) onParsedDataUpdate("teacher_answers", data.teacher_answers);
        onParsedDataUpdate("answers", res.data);
      } else {
        onParsedDataUpdate(type, res.data);
      }
    } catch (err: unknown) {
      setErrors((prev) => ({
        ...prev,
        [type]: err instanceof Error ? err.message : "Analysis failed",
      }));
    } finally {
      setAnalyzing((prev) => ({ ...prev, [type]: false }));
    }
  };

  const hasAnyParsedData = Object.keys(parsedData).length > 0;
  const isAnyAnalyzing = Object.values(analyzing).some(Boolean);

  return (
    <div className="space-y-6">
      {/* Model selector */}
      <div className="flex justify-end">
        <ModelSelector value={model} onChange={setModel} label="解析模型：" />
      </div>

      {/* Info note */}
      <p className="text-xs text-[var(--color-text-muted)] text-center">
        支援任意格式檔案（PDF、圖片、文字檔等）。若檔案中包含圖片、圖表或示意圖，AI 會自動將其轉換為文字描述，以確保後續分析完整準確。
      </p>

      {/* Upload zones */}
      <div className="grid grid-cols-1 md:grid-cols-2 gap-4">
        {zones.map((zone) => {
          const zoneData = parsedData[zone.type] as Record<string, unknown> | undefined;
          const isAnalyzing = analyzing[zone.type];
          const hasFiles = files[zone.type].length > 0;
          const hasParsed = !!zoneData;

          return (
            <div
              key={zone.type}
              className={`card p-6 transition-all ${hasParsed ? "border-[var(--color-success)]/50" : ""}`}
              onDragOver={(e) => e.preventDefault()}
              onDrop={(e) => handleDrop(zone.type, e)}
            >
              <div className="text-center mb-3">
                <span className="text-3xl">{zone.icon}</span>
                <h3 className="font-display text-lg font-semibold text-[var(--color-text)] mt-2">
                  {zone.label}
                </h3>
                <p className="text-sm text-[var(--color-text-muted)]">{zone.description}</p>
              </div>

              {/* Per-zone description */}
              <textarea
                value={descriptions[zone.type] || ""}
                onChange={(e) =>
                  setDescriptions((prev) => ({ ...prev, [zone.type]: e.target.value }))
                }
                placeholder={zone.placeholder}
                className="w-full mb-3 px-3 py-2 text-xs bg-[var(--color-surface)] border border-[var(--color-border)] rounded-lg text-[var(--color-text)] placeholder-[var(--color-text-muted)] resize-none focus:outline-none focus:border-[var(--color-primary)] transition-colors"
                rows={2}
              />

              {zone.type !== "questions" && parsers.length > 0 && (
                <div className="mb-3">
                  <label className="block text-xs text-[var(--color-text-muted)] mb-1">
                    解析工具
                  </label>
                  <select
                    value={parserByZone[zone.type] || "auto"}
                    onChange={(e) =>
                      setParserByZone((prev) => ({ ...prev, [zone.type]: e.target.value }))
                    }
                    className="input !py-1.5 text-xs w-full"
                    title={
                      parsers.find((p) => p.id === (parserByZone[zone.type] || "auto"))
                        ?.description ?? ""
                    }
                  >
                    {parsers.map((p) => (
                      <option key={p.id} value={p.id}>
                        {p.name}
                      </option>
                    ))}
                  </select>
                </div>
              )}

              <input
                ref={(el) => { fileInputRefs.current[zone.type] = el; }}
                type="file"
                multiple
                className="hidden"
                onChange={(e) => handleFileSelect(zone.type, e.target.files)}
              />

              <button
                onClick={() => fileInputRefs.current[zone.type]?.click()}
                className={`w-full py-6 border-2 border-dashed rounded-xl transition-all text-sm ${
                  hasFiles
                    ? "border-[var(--color-primary)] bg-[var(--color-primary)]/5"
                    : "border-[var(--color-border)] hover:border-[var(--color-primary)] hover:bg-[var(--color-primary)]/5"
                }`}
              >
                {hasFiles ? (
                  <div className="space-y-1">
                    {files[zone.type].map((f, i) => (
                      <p key={i} className="text-[var(--color-text)] truncate px-2">
                        {f.name}
                      </p>
                    ))}
                  </div>
                ) : (
                  <p className="text-[var(--color-text-muted)]">
                    點擊或拖放檔案至此
                  </p>
                )}
              </button>

              {/* Analyze button per zone */}
              <button
                onClick={() => handleAnalyze(zone.type)}
                disabled={!hasFiles || isAnalyzing}
                className="w-full mt-3 btn btn-primary py-2 text-sm disabled:opacity-50 disabled:cursor-not-allowed"
              >
                {isAnalyzing ? (
                  <span className="flex items-center justify-center gap-2">
                    <span className="w-4 h-4 border-2 border-white border-t-transparent rounded-full animate-spin" />
                    解析中...
                  </span>
                ) : hasParsed ? (
                  "重新解析"
                ) : (
                  "解析資料"
                )}
              </button>

              {/* Parsed status + summary */}
              {hasParsed && (
                <div className="mt-3 p-3 bg-[var(--color-background)] rounded-lg">
                  <p className="text-xs text-[var(--color-success)] font-semibold mb-1">
                    ✓ 解析完成
                    {(() => {
                      const directMeta = (zoneData as { _meta?: { parser?: string } })._meta;
                      const nestedMeta = (zoneData as {
                        student_answers?: { _meta?: { parser?: string } };
                      }).student_answers?._meta;
                      const parserName = directMeta?.parser ?? nestedMeta?.parser;
                      return parserName ? (
                        <span className="ml-2 text-[var(--color-text-muted)] font-normal">
                          (by {parserName})
                        </span>
                      ) : null;
                    })()}
                  </p>
                  <ZoneSummary type={zone.type} data={zoneData} />
                </div>
              )}

              {errors[zone.type] && (
                <p className="text-sm text-red-400 mt-2 text-center">{errors[zone.type]}</p>
              )}
            </div>
          );
        })}
      </div>

      {/* Full parsed data display */}
      {hasAnyParsedData && (
        <div className="space-y-4">
          <QuestionsTable data={parsedData.questions as Record<string, unknown> | undefined} />
          <StudentAnswersTable data={parsedData.student_answers as Record<string, unknown> | undefined} />
          <TeacherAnswersTable data={parsedData.teacher_answers as Record<string, unknown> | undefined} />
        </div>
      )}

      {/* Next step button */}
      {hasAnyParsedData && !isAnyAnalyzing && (
        <div className="text-center">
          <button
            onClick={onGoToStep2}
            className="btn btn-primary text-lg px-8 py-4"
          >
            確認資料，前往下一步 →
          </button>
        </div>
      )}
    </div>
  );
}

/** Compact summary shown inside each zone card */
function ZoneSummary({ type, data }: { type: string; data: Record<string, unknown> }) {
  if (type === "questions") {
    const questions = (data as { questions?: unknown[] }).questions;
    if (!questions) return null;
    return (
      <p className="text-xs text-[var(--color-text-muted)]">
        共 {questions.length} 題
      </p>
    );
  }
  if (type === "answers") {
    const sa = (data as { student_answers?: { students?: unknown[] } }).student_answers;
    const ta = (data as { teacher_answers?: { answers?: unknown[] } }).teacher_answers;
    const studentCount = sa?.students?.length ?? 0;
    const keyCount = ta?.answers?.length ?? 0;
    return (
      <p className="text-xs text-[var(--color-text-muted)]">
        共 {studentCount} 位學生 / 標準答案 {keyCount} 題
      </p>
    );
  }
  return null;
}

/* ── Parsed data tables ── */

function QuestionsTable({ data }: { data?: Record<string, unknown> }) {
  if (!data) return null;
  const questions = (data as { questions?: Array<{ number: number; text: string; options?: string[] | null }> }).questions;
  if (!questions?.length) return null;

  return (
    <div className="card p-5">
      <h3 className="font-display text-base font-semibold text-[var(--color-text)] mb-3">
        📝 考試題目（{questions.length} 題）
      </h3>
      <div className="overflow-x-auto">
        <table className="w-full text-sm">
          <thead>
            <tr className="border-b border-[var(--color-border)]">
              <th className="text-left py-2 px-3 text-[var(--color-text-muted)] w-12">#</th>
              <th className="text-left py-2 px-3 text-[var(--color-text-muted)]">題目</th>
            </tr>
          </thead>
          <tbody>
            {questions.map((q, i) => (
              <tr key={i} className="border-b border-[var(--color-border)]/50">
                <td className="py-2 px-3 text-[var(--color-primary)] font-bold">{q.number}</td>
                <td className="py-2 px-3 text-[var(--color-text)]">
                  <p>{q.text}</p>
                  {q.options && (
                    <div className="mt-1 text-xs text-[var(--color-text-muted)]">
                      {q.options.join(" | ")}
                    </div>
                  )}
                </td>
              </tr>
            ))}
          </tbody>
        </table>
      </div>
    </div>
  );
}

function StudentAnswersTable({ data }: { data?: Record<string, unknown> }) {
  if (!data) return null;
  const students = (data as { students?: Array<{ name: string; id?: string; answers: Array<{ question_number: number; answer: string | null }> }> }).students;
  if (!students?.length) return null;

  // Collect all question numbers across students
  const allQNums = Array.from(
    new Set(students.flatMap((s) => s.answers.map((a) => a.question_number)))
  ).sort((a, b) => a - b);

  return (
    <div className="card p-5">
      <h3 className="font-display text-base font-semibold text-[var(--color-text)] mb-3">
        👨‍🎓 學生答案（{students.length} 位學生）
      </h3>
      <div className="overflow-x-auto">
        <table className="w-full text-sm">
          <thead>
            <tr className="border-b border-[var(--color-border)]">
              <th className="text-left py-2 px-3 text-[var(--color-text-muted)] sticky left-0 bg-[var(--color-surface)]">學生</th>
              {allQNums.map((n) => (
                <th key={n} className="text-center py-2 px-3 text-[var(--color-text-muted)] min-w-[60px]">Q{n}</th>
              ))}
            </tr>
          </thead>
          <tbody>
            {students.map((s, i) => (
              <tr key={i} className="border-b border-[var(--color-border)]/50">
                <td className="py-2 px-3 text-[var(--color-text)] font-medium sticky left-0 bg-[var(--color-surface)]">
                  {s.name || s.id || `學生 ${i + 1}`}
                </td>
                {allQNums.map((n) => {
                  const ans = s.answers?.find((a) => a.question_number === n);
                  return (
                    <td key={n} className="text-center py-2 px-3 text-[var(--color-text-muted)]">
                      {ans?.answer ?? "-"}
                    </td>
                  );
                })}
              </tr>
            ))}
          </tbody>
        </table>
      </div>
    </div>
  );
}

function TeacherAnswersTable({ data }: { data?: Record<string, unknown> }) {
  if (!data) return null;
  const answers = (data as { answers?: Array<{ question_number: number; correct_answer: string; explanation?: string | null }> }).answers;
  if (!answers?.length) return null;

  return (
    <div className="card p-5">
      <h3 className="font-display text-base font-semibold text-[var(--color-text)] mb-3">
        ✅ 標準答案（{answers.length} 題）
      </h3>
      <div className="overflow-x-auto">
        <table className="w-full text-sm">
          <thead>
            <tr className="border-b border-[var(--color-border)]">
              <th className="text-left py-2 px-3 text-[var(--color-text-muted)] w-12">#</th>
              <th className="text-left py-2 px-3 text-[var(--color-text-muted)]">正確答案</th>
              <th className="text-left py-2 px-3 text-[var(--color-text-muted)]">解釋</th>
            </tr>
          </thead>
          <tbody>
            {answers.map((a, i) => (
              <tr key={i} className="border-b border-[var(--color-border)]/50">
                <td className="py-2 px-3 text-[var(--color-primary)] font-bold">Q{a.question_number}</td>
                <td className="py-2 px-3 text-[var(--color-success)] font-semibold">{a.correct_answer}</td>
                <td className="py-2 px-3 text-[var(--color-text-muted)]">{a.explanation || "-"}</td>
              </tr>
            ))}
          </tbody>
        </table>
      </div>
    </div>
  );
}