"use client";

import { useState, useRef } from "react";
import ReconstructionView from "@/components/reconstruction-view";
import DiagnosticsView from "@/components/diagnostics-view";

const MAX_LENGTH = 10000;

export default function ScenarioForm() {
  const [scenario, setScenario] = useState("");
  const [status, setStatus] = useState("idle"); // idle | loading | error | success
  const [result, setResult] = useState(null);
  const textareaRef = useRef(null);

  const handleSubmit = async (e) => {
    e.preventDefault();
    setStatus("loading");
    setResult(null);

    try {
      const res = await fetch("/api/analyse", {
        method: "POST",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({ scenario }),
      });

      const data = await res.json();

      if (res.ok && data.validationStatus === "valid") {
        setStatus("success");
        setResult(data);
      } else {
        setStatus("error");
        setResult(data);
      }
    } catch (err) {
      setStatus("error");
      setResult({ error: err.message || "Network request failed" });
    }
  };

  // Always show diagnostics when there's a result (even if validation failed)
  const hasDiagnostics = result && (result.reconstruction || result.modelName || result.responseDurationMs !== undefined);

  return (
    <div className="space-y-6">
      <form onSubmit={handleSubmit} className="space-y-4">
        <textarea
          ref={textareaRef}
          value={scenario}
          onChange={(e) => setScenario(e.target.value)}
          placeholder="Describe the scenario you want analysed..."
          rows={10}
          className="w-full rounded-lg border border-gray-300 px-4 py-3 text-sm focus:border-gray-500 focus:outline-none focus:ring-2 focus:ring-gray-400"
        />
        <div className="flex items-center justify-between">
          <span className="text-xs text-gray-400">{scenario.length}/{MAX_LENGTH}</span>
          <button
            type="submit"
            disabled={status === "loading" || !scenario.trim()}
            className="rounded-lg bg-gray-900 px-6 py-2.5 text-sm font-medium text-white transition hover:bg-gray-700 disabled:cursor-not-allowed disabled:opacity-40"
          >
            {status === "loading" ? "Analysing..." : "Analyse"}
          </button>
        </div>
      </form>

      {status === "error" && (
        <div className="space-y-3">
          {result?.error && (
            <div className="rounded-lg border border-red-300 bg-red-50 px-4 py-3 text-sm text-red-700 whitespace-pre-wrap">
              Error: {result.error}
            </div>
          )}
          {hasDiagnostics && result?.modelName && (
            <dl className="grid grid-cols-[auto_1fr] gap-x-4 gap-y-1.5 text-sm">
              <dt className="text-gray-500">Model</dt>
              <dd>{result.modelName}</dd>
              <dt className="text-gray-500">Duration</dt>
              <dd>{result.responseDurationMs != null ? `${result.responseDurationMs}ms` : "?"}</dd>
            </dl>
          )}
        </div>
      )}

      {status === "success" && result?.reconstruction && (
        <div className="space-y-4">
          <ReconstructionView reconstruction={result.reconstruction} />
          <DiagnosticsView result={result} />
        </div>
      )}

      {status === "error" && result?.reconstruction && (
        <div className="space-y-3">
          <div className="rounded-lg border border-yellow-300 bg-yellow-50 px-4 py-2 text-sm text-yellow-800">
            ⚠ Partial result — some fields failed validation. Showing what was accepted.
          </div>
          <ReconstructionView reconstruction={result.reconstruction} partial />
        </div>
      )}

      {status === "loading" && (
        <div className="py-12 text-center text-sm text-gray-400">Waiting for model response...</div>
      )}
    </div>
  );
}