"use client";

import { useState, useEffect, useCallback } from "react";

export function GenerateTab({ importType }: { importType: "flashcards" | "quizzes" | "connections" | "crossword" }) {
  const [instructions, setInstructions] = useState("");
  const [loading, setLoading] = useState(true);
  const [saving, setSaving] = useState(false);
  const [saveResult, setSaveResult] = useState<"success" | "error" | null>(null);
  const [copied, setCopied] = useState(false);
  const [packCount, setPackCount] = useState(1);
  const [loadError, setLoadError] = useState<string | null>(null);

  const batchOverride = importType === "connections" && packCount > 1
    ? `TEMPORARY BATCH OVERRIDE:\nGenerate exactly ${packCount} distinct Connections packs. Return one raw JSON array containing exactly ${packCount} objects that each follow the schema below. Make the packs meaningfully different from one another. This override takes precedence over any later instruction to return one object.\n\n`
    : "";
  const displayedInstructions = `${batchOverride}${instructions}`;

  const loadInstructions = useCallback(async (signal?: AbortSignal) => {
    setLoading(true);
    setLoadError(null);
    try {
      const response = await fetch(`/api/settings/llm-instructions?type=${importType}`, { signal });
      if (!response.ok) throw new Error("Instructions could not be loaded.");
      const data = await response.json() as { value?: unknown };
      if (typeof data.value !== "string") throw new Error("The server returned invalid instructions.");
      setInstructions(data.value);
    } catch (error) {
      if (signal?.aborted) return;
      setLoadError(error instanceof Error ? error.message : "Instructions could not be loaded.");
    } finally {
      if (!signal?.aborted) setLoading(false);
    }
  }, [importType]);

  useEffect(() => {
    const controller = new AbortController();
    const timer = window.setTimeout(() => void loadInstructions(controller.signal), 0);
    return () => {
      window.clearTimeout(timer);
      controller.abort();
    };
  }, [loadInstructions]);

  async function handleSave() {
    setSaving(true);
    setSaveResult(null);
    try {
      const res = await fetch(`/api/settings/llm-instructions?type=${importType}`, {
        method: "PATCH",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({ value: instructions }),
      });
      if (!res.ok) throw new Error("Failed to save");
      setSaveResult("success");
    } catch {
      setSaveResult("error");
    } finally {
      setSaving(false);
      setTimeout(() => setSaveResult(null), 2500);
    }
  }

  async function handleReset() {
    if (!confirm("Reset to default instructions?")) return;
    setSaving(true);
    try {
      const res = await fetch(`/api/settings/llm-instructions?type=${importType}`, {
        method: "PATCH",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({ value: "__RESET__" }),
      });
      if (!res.ok) throw new Error("Failed to reset instructions");
      const data = await res.json();
      if (typeof data.value !== "string") throw new Error("Invalid reset response");
      setInstructions(data.value);
      setSaveResult("success");
    } catch {
      setSaveResult("error");
    } finally {
      setSaving(false);
    }
  }

  async function handleCopy() {
    try {
      await navigator.clipboard.writeText(displayedInstructions);
      setCopied(true);
      setTimeout(() => setCopied(false), 2000);
    } catch {
      setLoadError("Clipboard access failed. Select and copy the instructions manually.");
    }
  }

  if (loading) {
    return <div className="animate-subtle-pulse text-text-muted">Loading instructions...</div>;
  }

  if (loadError && !instructions) {
    return (
      <div role="alert" className="rounded-xl border border-error/30 bg-error-bg p-4 text-error">
        <p>{loadError}</p>
        <button onClick={() => void loadInstructions()} className="mt-3 min-h-10 rounded-lg border border-error/40 px-4 text-sm font-bold">Retry</button>
      </div>
    );
  }

  return (
    <div className="space-y-4">
      {loadError && <p role="alert" className="rounded-lg bg-error-bg p-3 text-sm text-error">{loadError}</p>}
      <p className="text-sm text-text-secondary">
        Copy these instructions and paste them into an LLM chat along with your study material. The LLM will generate JSON you can paste into the Import tab.
      </p>

      {importType === "connections" && (
        <div className="rounded-xl border border-border bg-bg-surface-alt/60 p-4">
          <div className="flex items-center justify-between gap-4">
            <div>
            <label htmlFor="connections-pack-count" className="text-sm font-bold text-text-heading">Number of game packs</label>
            <p className="text-xs text-text-muted">This temporarily updates the copied prompt. Your saved instructions stay unchanged.</p>
            </div>
            <output htmlFor="connections-pack-count" className="grid h-11 min-w-12 place-items-center rounded-lg border border-border bg-bg-surface px-3 text-lg font-extrabold text-text-heading">{packCount}</output>
          </div>
          <input id="connections-pack-count" type="range" min={1} max={10} step={1} value={packCount} onChange={(event) => setPackCount(Number(event.target.value))} className="mt-4 w-full accent-primary" />
          <div className="mt-1 flex justify-between text-[10px] font-bold text-text-muted" aria-hidden><span>1</span><span>5</span><span>10</span></div>
        </div>
      )}

      <textarea
        value={displayedInstructions}
        onChange={(event) => setInstructions(batchOverride && event.target.value.startsWith(batchOverride) ? event.target.value.slice(batchOverride.length) : event.target.value)}
        rows={14}
        className="w-full px-4 py-3 rounded-lg border border-border bg-bg-surface-alt/50 text-sm text-text-body font-mono leading-relaxed focus:outline-none focus:ring-2 focus:ring-primary/30 focus:border-primary transition-all duration-200 resize-y"
      />

      <div className="flex items-center gap-2">
        <button
          onClick={handleCopy}
          className="inline-flex items-center gap-2 px-4 py-2 rounded-lg bg-primary text-white text-sm font-medium hover:bg-primary-hover transition-all duration-200 cursor-pointer"
        >
          {copied ? (
            <>
              <svg className="w-4 h-4" fill="none" stroke="currentColor" viewBox="0 0 24 24">
                <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M5 13l4 4L19 7" />
              </svg>
              Copied!
            </>
          ) : (
            <>
              <svg className="w-4 h-4" fill="none" stroke="currentColor" viewBox="0 0 24 24">
                <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M8 5H6a2 2 0 00-2 2v12a2 2 0 002 2h10a2 2 0 002-2v-1M8 5a2 2 0 002 2h2a2 2 0 002-2M8 5a2 2 0 012-2h2a2 2 0 012 2m0 0h2a2 2 0 012 2v3m2 4H10m0 0l3-3m-3 3l3 3" />
              </svg>
              Copy to Clipboard
            </>
          )}
        </button>
        <button
          onClick={handleSave}
          disabled={saving}
          className={`inline-flex items-center gap-2 px-4 py-2 rounded-lg border text-sm transition-all duration-200 cursor-pointer disabled:opacity-50 ${
            saveResult === "success" ? "border-success text-success bg-success-bg" :
            saveResult === "error" ? "border-error text-error bg-error-bg" :
            "border-border text-text-secondary hover:bg-bg-surface-alt"
          }`}
        >
          {saving ? "Saving..." : 
           saveResult === "success" ? (
             <>
               <svg className="w-4 h-4" fill="none" stroke="currentColor" viewBox="0 0 24 24">
                 <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M5 13l4 4L19 7" />
               </svg>
               Saved!
             </>
           ) : 
           saveResult === "error" ? "Failed to Save" : 
           "Save Changes"}
        </button>
        <button
          onClick={handleReset}
          disabled={saving}
          className="px-4 py-2 rounded-lg text-sm text-text-muted hover:text-error hover:bg-error-bg transition-all duration-200 cursor-pointer disabled:opacity-50"
        >
          Reset to Default
        </button>
      </div>
    </div>
  );
}