"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 | partial
  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 if (data.success) {
        // Success in analysis but validation may be partial
        setStatus("success");
        setResult(data);
      } else {
        setStatus("error");
        setResult(data);
      }
    } catch (err) {
      setStatus("error");
      setResult({ error: err.message || "Network request failed" });
    }
  };

  // Determine if we have meaningful content to display
  const hasClassification = result?.inputClassification;
  const hasReconstruction = result?.reconstruction;
  const hasNextQuestion = result?.nextQuestion;
  const hasEvidence = result?.evidence && result.evidence.length > 0;
  const hasMeaningfulContent = hasClassification || hasReconstruction || hasNextQuestion || hasEvidence;

  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>

      {/* Error state */}
      {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>
          )}
          {/* Show partial content even on validation failure */}
          {(hasClassification || hasReconstruction) && (
            <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>
          )}
          {hasReconstruction && (
            <ReconstructionView reconstruction={result} partial />
          )}
        </div>
      )}

      {/* Success state */}
      {status === "success" && hasMeaningfulContent && (
        <div className="space-y-4">
          <ReconstructionView reconstruction={result} />
        </div>
      )}

      {/* Always show diagnostics when we have any result */}
      {(hasClassification || hasReconstruction || hasNextQuestion) && (
        <DiagnosticsView result={result} />
      )}

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

      {/* Empty state */}
      {status === "idle" && (
        <div className="rounded-lg border border-dashed border-gray-300 bg-gray-50 px-6 py-8 text-center">
          <p className="text-sm text-gray-400">Enter a scenario above and click Analyse to begin.</p>
        </div>
      )}

      {/* Invalid result with no partial data */}
      {status === "error" && !result?.error && !hasMeaningfulContent && (
        <div className="rounded-lg border border-yellow-300 bg-yellow-50 px-4 py-2 text-sm text-yellow-800">
          Validation failed — no structured output was produced.
        </div>
      )}
    </div>
  );
}