"use client";

import React, { useEffect, useRef, useState } from "react";
import { loadInvestigation, saveInvestigation } from "@/lib/storage/investigation-storage";
import Link from "next/link";

export default function ReportPage({ params }) {
  const routeId = (typeof params === "object" && params?.id != null) ? String(params.id) : "";
  const [existing, setExisting] = useState(null);
  const [hydrated, setHydrated] = useState(false);
  const [generationLoading, setGenerationLoading] = useState(false);
  const [generationError, setGenerationError] = useState(false);
  const [updateLoading, setUpdateLoading] = useState(false);

  const generationAttempted = useRef(false);

  useEffect(() => {
    setExisting(loadInvestigation(routeId));
    setHydrated(true);
  }, []);

  // First-generation: create report when none persists (v0.58)
  useEffect(() => {
    if (!hydrated) return;
    if (existing?.investigationReport) return;
    if (generationAttempted.current) return;
    generationAttempted.current = true;

    const situationGraph = existing?.situationGraph;
    const findings = existing?.findings ?? [];

    if (!situationGraph) {
      setGenerationError(true);
      return;
    }

    (async () => {
      setGenerationLoading(true);
      try {
        const res = await fetch("/api/cases/overview", {
          method: "POST",
          headers: { "Content-Type": "application/json" },
          body: JSON.stringify({ situationGraph, findings }),
        });

        if (!res.ok) {
          setGenerationError(true);
          return;
        }

        const data = await res.json();
        if (data.success) {
          /* ── v0.59a — provenance: record generation revision (does NOT change Investigation revision) ── */
          const rev = existing?.investigationRevision ?? 0;
          const reportData = { understanding: data.understanding, plausibleInterpretations: data.plausibleInterpretations, hasPlausibleInterpretations: true, generatedFromRevision: rev };
          setExisting((p) => {
            saveInvestigation({ ...p, investigationReport: reportData });
            return { ...p, investigationReport: reportData };
          });
        } else {
          setGenerationError(true);
        }
      } catch {
        setGenerationError(true);
      } finally {
        setGenerationLoading(false);
      }
    })();
  }, [hydrated, existing]);

  // Manual Report update (v0.59b — freshness manual update)
  const handleUpdateReport = async () => {
    if (updateLoading) return;
    setUpdateLoading(true);

    const snap = loadInvestigation(routeId);
    const situationGraph = snap?.situationGraph;
    const findings = snap?.findings ?? [];
    const rev = snap?.investigationRevision ?? 0;

    if (!situationGraph) {
      setUpdateLoading(false);
      return;
    }

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

      if (!res.ok) {
        setUpdateLoading(false);
        return;
      }

      const data = await res.json();
      if (data.success) {
        const reportData = { understanding: data.understanding, plausibleInterpretations: data.plausibleInterpretations, hasPlausibleInterpretations: true, generatedFromRevision: rev };
        setExisting((p) => {
          saveInvestigation({ ...p, investigationReport: reportData });
          return { ...p, investigationReport: reportData };
        });
      }
    } catch {
      /* failure: retain existing Report and updateAvailable state */
    } finally {
      setUpdateLoading(false);
    }
  };

  const report = existing?.investigationReport || null;
  const scenario = hydrated ? (existing?.scenario || "") : null;

  const paragraphs = (report?.understanding || "")
    .split("\n")
    .filter(Boolean);

  return (
    <main className="mx-auto max-w-[800px] px-6 py-16">
      <h1 className="mb-2 text-[15px] font-bold tracking-[.2em] uppercase text-teal-700/90">
        Investigation Report
      </h1>

      {/* Report freshness — only when a Report exists */}
      {report ? (
        <div className="mt-6 flex items-center gap-3">
          {existing?.investigationRevision === report.generatedFromRevision ? (
            <span className="text-[11px] font-semibold tracking-wider uppercase text-teal-700/70">Current</span>
          ) : (
            <div className="flex items-center gap-3">
              <span className="text-[11px] font-semibold tracking-wider uppercase text-gray-500">Update available</span>
              <span className="text-xs text-gray-400">The investigation has changed since this report was generated.</span>
              <button
                type="button"
                onClick={handleUpdateReport}
                disabled={updateLoading}
                className="rounded-lg border border-teal-600 bg-white px-3 py-1.5 text-[11px] font-semibold tracking-wider uppercase text-teal-700 hover:bg-teal-50 transition disabled:opacity-40"
              >
                {updateLoading ? "Updating&#8230;" : "Update report"}
              </button>
            </div>
          )}
        </div>
      ) : null}

      {/* Situation */}
      {scenario && (
        <div className="mt-8 rounded-xl border-[2.5px] border-teal-300/70 bg-gradient-to-b from-teal-50/60 to-white px-8 pt-6 pb-7 shadow-sm">
          <h2 className="mb-3 text-[11px] font-bold tracking-[.18em] uppercase text-teal-700/70">
            Situation
          </h2>
          <p className="text-base leading-relaxed text-gray-800 whitespace-pre-wrap">
            {scenario}
          </p>
        </div>
      )}

      {/* What we understand */}
      {report ? (
        <>
          {paragraphs.length > 0 ? (
            paragraphs.map((p, i) => (
              <div key={i} className="mt-6 rounded-xl border-[2.5px] border-teal-300/70 bg-gradient-to-b from-teal-50/60 to-white px-8 pt-6 pb-7 shadow-sm">
                <h2 className="mb-3 text-[11px] font-bold tracking-[.18em] uppercase text-teal-700/70">
                  What we understand
                </h2>
                <p className="text-base leading-relaxed text-gray-800">{p}</p>
              </div>
            ))
          ) : (
            <div className="mt-6 rounded-xl border-[2.5px] border-teal-300/70 bg-gradient-to-b from-teal-50/60 to-white px-8 pt-6 pb-7 shadow-sm">
              <h2 className="mb-3 text-[11px] font-bold tracking-[.18em] uppercase text-teal-700/70">
                What we understand
              </h2>
              <p className="text-base leading-relaxed text-gray-800">{report.understanding || ""}</p>
            </div>
          )}

          {/* What remains plausible — conditional */}
          {report.hasPlausibleInterpretations && report.plausibleInterpretations ? (
            <div className="mt-6 rounded-xl border-[2.5px] border-blue-300/70 bg-gradient-to-b from-blue-50/60 to-white px-8 pt-6 pb-7 shadow-sm">
              <h2 className="mb-3 text-[11px] font-bold tracking-[.18em] uppercase text-blue-700/70">
                What remains plausible
              </h2>
              <p className="text-base leading-relaxed text-gray-800 italic">
                {report.plausibleInterpretations}
              </p>
            </div>
          ) : null}
        </>
      ) : (
        /* Skeleton / loading state when no persisted report exists */
        <>
          <div className="mt-8 rounded-xl border-[2.5px] border-gray-200 bg-gray-50/50 px-8 pt-6 pb-7 shadow-sm">
            <h2 className="mb-3 text-[11px] font-bold tracking-[.18em] uppercase text-gray-400">
              What we understand
            </h2>
            {generationLoading ? (
              <div className="flex flex-col gap-3 py-2" aria-live="polite">
                <span className="text-[11px] font-semibold tracking-wider text-gray-400 uppercase">Generating report&#8230;</span>
                {[0, 1, 2].map((i) => (
                  <div key={i} className="h-4 w-full rounded animate-pulse" style={{ backgroundColor: "rgb(229 231 235)", animationDelay: `${i * 150}ms`, width: i === 1 ? "80%" : i === 2 ? "65%" : "90%" }} />
                ))}
              </div>
            ) : generationError ? (
              <p className="text-sm text-red-600">Report generation failed. You may try again from the Investigation page.</p>
            ) : null}
          </div>
        </>
      )}

      {/* Back to investigation */}
      <div className="mt-10">
        <Link
          href={`/investigations/${routeId}`}
          className="rounded-lg border border-teal-600 bg-white px-4 py-2 text-sm font-medium text-teal-700 hover:bg-teal-50 transition"
        >
          Back to investigation
        </Link>
      </div>

      {/* Back to portfolio */}
      <div className="mt-3">
        <Link
          href="/"
          className="rounded-lg border border-teal-600 bg-white px-4 py-2 text-sm font-medium text-teal-700 hover:bg-teal-50 transition"
        >
          Back to portfolio
        </Link>
      </div>
    </main>
  );
}