"use client";

import React, { useState, useRef, useEffect, useMemo } from "react";
import DiagnosticsView from "@/components/diagnostics-view";
import GraphUpdateView from "@/components/graph-update-view";
import SituationGraphView from "@/components/situation-graph-view";

// ── Technical summary detector (main view filters these) ───
const TECHNICAL_PATTERNS = [
  /nodes?\s*[:\d]/i,
  /edges?\s*[:\d]/i,
  /\b(?:unknown|observation|conclusion)\b\s/i,
  /\bsorted\b/i,
  /by_kind/i,
  /\b(?:node|edge|unknown|state)\s+count/i,
];

function isTechnicalSummary(summary) {
  if (!summary || typeof summary !== "string") return false;
  const trimmed = summary.trim();
  if (!trimmed) return false;
  for (const p of TECHNICAL_PATTERNS) {
    if (p.test(trimmed)) return true;
  }
  return false;
}

function resolveCurrentSummary(currentSummary) {
  if (isTechnicalSummary(currentSummary)) {
    return null;
  }
  return currentSummary || null;
}

// ── Status message pools for loading feedback ────────────────
const INITIAL_MESSAGES = [
  { min: 0, text: "Reading your situation" },
  { min: 10, text: "Building a structured understanding" },
  { min: 25, text: "Identifying what is known and still unclear" },
  { min: 45, text: "Selecting the next useful question" },
];

const UPDATE_MESSAGES = [
  { min: 0, text: "Considering your answer" },
  { min: 10, text: "Updating the situation" },
  { min: 25, text: "Checking what changed" },
  { min: 45, text: "Choosing the next question" },
];

function useLoadingStatus(messages, isLoading) {
  const [elapsed, setElapsed] = useState(0);
  const startRef = useRef(null);

  useEffect(() => {
    if (isLoading) {
      startRef.current = Date.now();
      const iv = setInterval(() => {
        setElapsed(Math.floor((Date.now() - startRef.current) / 1000));
      }, 1000);
      return () => clearInterval(iv);
    } else {
      setElapsed(0);
      startRef.current = null;
    }
  }, [isLoading]);

  const currentMessage = useMemo(() => {
    if (!messages || messages.length === 0) return "";
    let msg = messages[0].text;
    for (const m of messages) {
      if (elapsed >= m.min) msg = m.text;
    }
    return msg;
  }, [messages, elapsed]);

  return { elapsed, currentMessage };
}

// ── Spinner component ───────────────────────────────────────
function ActivitySpinner() {
  return (
    <span
      className="inline-block h-4 w-4 border-[2px] border-gray-300 border-t-gray-600 rounded-full"
      style={{ animation: "spin 1s linear infinite" }}
    />
  );
}

// ── Current investigation card (prominent hero section) ──────
function CurrentInvestigationCard({ selectedQuestion, graph }) {
  if (!selectedQuestion) return null;

  const q = typeof selectedQuestion === "string" ? selectedQuestion : selectedQuestion.question;
  if (!q) return null;

  // Derive meaningful context from the active node only when it adds value
  let whyMattersText = null;
  if (graph?.activeUnknownNodeId && graph.nodes) {
    const activeNode = graph.nodes.find((n) => n.id === graph.activeUnknownNodeId);
    if (activeNode?.description && activeNode.description !== activeNode.label) {
      whyMattersText = activeNode.description;
    }
  }

  return (
    <div className="investigation-card rounded-lg border-2 border-green-300 bg-green-50 p-6">
      <h2 className="mb-2 text-sm font-bold uppercase tracking-wide text-green-700">
        Current investigation
      </h2>
      <p className="text-xl font-semibold leading-snug text-gray-900">{q}</p>
      {whyMattersText && (
        <div className="mt-4 space-y-1">
          <h3 className="text-xs font-bold uppercase tracking-wide text-green-800">Why this matters</h3>
          <p className="text-sm text-gray-700">{whyMattersText}</p>
        </div>
      )}
    </div>
  );
}

// ── Outcome helpers ───────────────────────────────────────────

function hasGenuineCompletion(graph) {
  if (!graph || !graph.nodes?.length) return false;
  const resolvedIds = new Set(graph.resolvedNodeIds || []);
  const unresolvedCount = graph.nodes.filter(
    (n) => n.kind === "unknown" && n.status !== "resolved" && !resolvedIds.has(n.id),
  ).length;
  if (unresolvedCount > 0) return false;
  if (graph.activeUnknownNodeId) {
    const active = graph.nodes.find((n) => n.id === graph.activeUnknownNodeId);
    if (active && active.status !== "resolved" && !resolvedIds.has(active.id)) return false;
  }
  return true;
}

// ── Completion card (terminal state when all unknowns resolved) ─
function CompletionCard() {
  return (
    <div className="rounded-lg border border-green-300 bg-green-50 px-5 py-6 text-center">
      <h2 className="mb-1 text-sm font-bold uppercase tracking-wide text-green-700">Investigation complete</h2>
      <p className="text-base text-gray-800">You have provided enough information. The situation has been fully investigated.</p>
    </div>
  );
}

// ── Evidence exhaustion card (terminal state) ─────────────────
function EvidenceExhaustedCard({ noQuestionReason }) {
  let message = "There is not yet enough evidence to guide the next step.";
  if (noQuestionReason) {
    const reason = String(noQuestionReason);
    if (reason.toLowerCase().includes("insufficient")) {
      message = reason;
    }
  }
  return (
    <div className="rounded-lg border border-gray-200 bg-gray-50 px-5 py-6 text-center">
      <h2 className="mb-1 text-sm font-bold uppercase tracking-wide text-gray-500">Further investigation needed</h2>
      <p className="text-base text-gray-700">{message}</p>
    </div>
  );
}

// ── Current understanding card ────────────────────────────────
function CurrentUnderstandingCard({ currentSummary }) {
  const summary = resolveCurrentSummary(currentSummary);

  if (!summary) return null;

  return (
    <div className="rounded-lg border border-gray-200 bg-white p-5">
      <h2 className="mb-3 text-sm font-semibold uppercase tracking-wide text-gray-500">
        Current understanding
      </h2>
      <p className="text-sm leading-relaxed text-gray-700">{summary}</p>
    </div>
  );
}

// ── Investigation history card (readable notebook style) ──────
function InvestigationHistoryCard({ turn }) {
  const isCollapsed = turn._collapsed;

  return (
    <details
      className="rounded-lg border border-gray-100 bg-gray-50/60"
      key={turn.id}
      open={!isCollapsed}
    >
      <summary className="cursor-pointer px-4 py-2 text-sm font-medium text-gray-700 hover:text-gray-900">
        {isCollapsed ? "Q: " : "✓ "}
        {turn.question.length > 60 && !isCollapsed
          ? turn.question.slice(0, 60) + "…"
          : turn.question}
        {!isCollapsed && (
          <span className="ml-2 text-xs font-normal text-gray-400">— answered</span>
        )}
      </summary>

      <div className="px-4 pb-3 pt-1 space-y-2">
        <p><strong>Your answer</strong></p>
        <p className="text-gray-700">{turn.answer}</p>

        {turn.acknowledgement && (
          <>
            <hr className="border-gray-200" />
            <p><strong>What changed</strong></p>
            <p className="italic text-gray-500">{turn.acknowledgement}</p>
          </>
        )}
      </div>
    </details>
  );
}

// ── Investigation history section ─────────────────────────────
function InvestigationHistory({ turns }) {
  if (!turns || turns.length === 0) return null;

  const latestId = turns[turns.length - 1].id;

  return (
    <div className="space-y-3">
      <h2 className="text-xs font-bold uppercase tracking-wider text-gray-400">
        Investigation history
      </h2>
      <div className="space-y-2">
        {turns.map((turn) => (
          <InvestigationHistoryCard key={turn.id} turn={{ ...turn, _collapsed: turn.id !== latestId }} />
        ))}
      </div>
    </div>
  );
}

// ── Original situation (collapsed by default) ─────────────────
function OriginalSituation({ scenario, centralStatement }) {
  if (!scenario) return null;

  return (
    <details className="rounded-lg border border-gray-200 bg-gray-50">
      <summary className="cursor-pointer px-5 py-3 text-sm font-medium text-gray-600 hover:text-gray-800">
        Original situation
      </summary>
      <div className="border-t border-gray-200 px-5 pb-4 pt-3 space-y-3">
        {centralStatement && (
          <p className="text-sm text-gray-600 italic">{centralStatement}</p>
        )}
        <p className="whitespace-pre-wrap text-sm text-gray-800">{scenario}</p>
      </div>
    </details>
  );
}

// ── Update acknowledgement ────────────────────────────────────
function UpdateAcknowledgement({ updateResult }) {
  if (!updateResult) return null;

  const summary = updateResult.summary;
  const hasResolvedNodes = updateResult.resolvedUnknownNodeIds?.length > 0;
  const hasAffectedNodes = updateResult.affectedNodeIds?.length > 0;
  const graph = updateResult.updatedSituationGraph;

  function getNodeText(nodeId) {
    if (!graph?.nodes) return String(nodeId);
    const node = graph.nodes.find((n) => n.id === nodeId);
    if (node) {
      const parts = [node.label];
      if (node.status !== "resolved") {
        parts.push(node.status);
      }
      return parts.join(" ");
    }
    return String(nodeId);
  }

  let changedText;
  if (hasResolvedNodes) {
    const items = [];
    for (const id of updateResult.resolvedUnknownNodeIds.slice(0, 3)) {
      items.push(getNodeText(id));
    }
    if (updateResult.resolvedUnknownNodeIds.length > 3) {
      items.push(`and ${updateResult.resolvedUnknownNodeIds.length - 3} more resolved`);
    }
    changedText = items.join(". ") + ".";
  } else if (hasAffectedNodes) {
    const items = [];
    for (const id of updateResult.affectedNodeIds.slice(0, 3)) {
      items.push(getNodeText(id));
    }
    if (updateResult.affectedNodeIds.length > 3) {
      items.push(`and ${updateResult.affectedNodeIds.length - 3} more affected`);
    }
    changedText = items.join(". ") + ".";
  } else if (updateResult.changesApplied) {
    const ca = updateResult.changesApplied;
    const parts = [];
    if (ca.addedNodeCount) parts.push(`${ca.addedNodeCount} node(s) added`);
    if (ca.updatedNodeCount) parts.push(`${ca.updatedNodeCount} node(s) updated`);
    if (ca.addedEdgeCount) parts.push(`${ca.addedEdgeCount} edge(s) added`);
    if (ca.removedEdgeCount) parts.push(`${ca.removedEdgeCount} edge(s) removed`);
    changedText = parts.length > 0 ? parts.join(", ") : null;
  }

  const displayMessage = summary || changedText || "Your answer has been added to the investigation.";

  return (
    <div className="rounded-lg border border-blue-100 bg-blue-50/80 px-5 py-3 text-sm text-blue-900">
      {displayMessage}
    </div>
  );
}

// ── Developer details disclosure ──────────────────────────────
function DeveloperDetails({ graph, selectedQuestion, diagnostics, newlySurfacedNodeIds, updateResult }) {
  return (
    <details className="rounded-lg border border-gray-200 bg-gray-50">
      <summary className="cursor-pointer px-5 py-3 text-sm font-medium text-gray-600 hover:text-gray-800">
        Developer details
      </summary>
      <div className="border-t border-gray-200 px-5 pb-4 pt-3 space-y-4">
        {graph && (
          <SituationGraphView
            situationGraph={graph}
            selectedQuestion={selectedQuestion}
            newlySurfacedNodeIds={newlySurfacedNodeIds}
          />
        )}
        {updateResult && (
          <GraphUpdateView updateResult={{ ...updateResult, previousSituationGraph: graph }} />
        )}
        {diagnostics && <DiagnosticsView result={{ diagnostics }} />}
      </div>
    </details>
  );
}

// ── Loading overlay (for both start and update) ───────────────
function LoadingOverlay({ isLoading, elapsed, currentMessage, variant }) {
  if (!isLoading) return null;

  const messages = variant === "update" ? UPDATE_MESSAGES : INITIAL_MESSAGES;
  let statusText = messages[0].text;
  for (const m of messages) {
    if (elapsed >= m.min) statusText = m.text;
  }

  return (
    <div className="rounded-lg border border-gray-200 bg-blue-50 px-5 py-6" role="status" aria-busy="true">
      <div className="flex items-center gap-3">
        <ActivitySpinner />
        <span className="text-base font-medium text-blue-900">Working through your situation</span>
      </div>
      <p className="mt-2 text-sm text-blue-700">{statusText}</p>
      <p className="mt-1 text-xs text-blue-500" aria-live="polite">
        This has been running for {elapsed}s.
        {variant === "initial" && elapsed >= 45 && (
          <span className="block mt-1">This can take around a minute with the current local model.</span>
        )}
      </p>
    </div>
  );
}

// ── Main workspace component ──────────────────────────────────
export default function ReasoningWorkspace({
  scenario,
  status,
  updateStatus,
  result,
  answer,
  setAnswer,
  onAnswerSubmit,
  lastSubmittedAnswer,
}) {
  const [investigationHistory, setInvestigationHistory] = useState([]);
  const turnCounter = useRef(0);
  const pendingTurnRef = useRef(null);

  // Capture the current selected question at submit time (not from a stale ref)
  const capturePendingTurn = (selectedQuestion, answerText) => {
    if (!selectedQuestion || !answerText?.trim()) return null;
    const q = typeof selectedQuestion === "string" ? selectedQuestion : selectedQuestion.question;
    if (!q) return null;
    turnCounter.current += 1;
    return {
      id: `turn-${turnCounter.current}`,
      question: q,
      answer: answerText.trim(),
      acknowledgement: null,
    };
  };

  // Append the captured pending turn to history after a successful update only
  useEffect(() => {
    const pending = pendingTurnRef.current;
    if (!pending || updateStatus !== "success") return;

    setInvestigationHistory((prev) => [
      ...prev,
      { ...pending, acknowledgement: result?.summary || null },
    ]);
    pendingTurnRef.current = null;
  }, [updateStatus, result]);

  const handleUpdateCaptureAndSubmit = async (e) => {
    e.preventDefault();
    if (!answer?.trim() || !result?.selectedQuestion) return;
    pendingTurnRef.current = capturePendingTurn(result.selectedQuestion, answer);
    await onAnswerSubmit(e);
  };

  const { elapsed: startElapsed, currentMessage: startMsg } = useLoadingStatus(
    INITIAL_MESSAGES,
    status === "loading"
  );

  const { elapsed: updateElapsed, currentMessage: updateMsg } = useLoadingStatus(
    UPDATE_MESSAGES,
    updateStatus === "loading"
  );

  const isUpdating = updateStatus === "loading";
  const hasSelectedQuestion = Boolean(result?.selectedQuestion);

  const canAnswer =
    status === "success" &&
    !isUpdating &&
    Boolean(result?.situationGraph) &&
    hasSelectedQuestion;

  const selectedQ = result?.selectedQuestion ?? null;
  const graph = result?.situationGraph ?? null;
  const diagnostics = result?.diagnostics ?? null;
  const newlySurfacedNodeIds = result?.newlySurfacedNodeIds || [];
  const noQuestionReason = diagnostics?.noQuestionReason ?? null;

  const genuineCompletion = hasGenuineCompletion(graph);

  return (
    <div className="space-y-6">
      {/* ── Loading overlays ─────────────────────────────── */}
      {status === "loading" && (
        <LoadingOverlay
          elapsed={startElapsed}
          currentMessage={startMsg}
          variant="initial"
        />
      )}
      {updateStatus === "loading" && (
        <LoadingOverlay
          elapsed={updateElapsed}
          currentMessage={updateMsg}
          variant="update"
        />
      )}

      {/* ── No graph produced after initial analysis ───────── */}
      {(status === "success" || status === "error") && !graph ? (
        <div className="rounded-lg border border-yellow-300 bg-yellow-50 px-4 py-3 text-sm text-yellow-800">
          {noQuestionReason
            ? "Validation failed — no structured graph output was produced."
            : "The analysis completed but did not produce a structured result."}
        </div>
      ) : (
        <>
          {/* ── 1. Current investigation (or terminal state) ─ */}
          {canAnswer && <CurrentInvestigationCard selectedQuestion={selectedQ} graph={graph} />}

          {/* Terminal states occupy the hero position when no question */}
          {status === "success" && !canAnswer && graph && genuineCompletion && (
            <CompletionCard />
          )}
          {status === "success" && !canAnswer && graph && !genuineCompletion && updateStatus !== "success" && (
            <EvidenceExhaustedCard noQuestionReason={noQuestionReason} />
          )}

          {/* ── 2. Post-update acknowledgement ─────────────── */}
          {updateStatus === "success" && canAnswer && <UpdateAcknowledgement updateResult={result} />}

          {/* ── 3. Current understanding ───────────────────── */}
          {canAnswer && graph && <CurrentUnderstandingCard currentSummary={graph.currentSummary} />}

          {/* ── 4. Investigation history ───────────────────── */}
          <InvestigationHistory turns={investigationHistory} />

          {/* ── 5. Response form (immediately after Current investigation) ─ */}
          {canAnswer && (
            <form onSubmit={handleUpdateCaptureAndSubmit} className="space-y-4 rounded-lg border border-gray-200 bg-white p-5">
              <div>
                <label htmlFor="rw-answer" className="mb-2 block text-sm font-medium text-gray-700">
                  Your response
                </label>
                <textarea
                  id="rw-answer"
                  value={answer}
                  onChange={(e) => setAnswer(e.target.value)}
                  rows={4}
                  disabled={updateStatus === "loading"}
                  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 disabled:cursor-not-allowed disabled:opacity-60"
                  placeholder="Enter the answer to the selected question..."
                />
              </div>
              <div className="flex items-center justify-between">
                <p className="text-xs text-gray-400">
                  {updateStatus === "loading" ? "Updating..." : "One update turn only in this prototype."}
                </p>
                <button
                  type="submit"
                  disabled={updateStatus === "loading" || !answer.trim()}
                  className="rounded-lg bg-blue-700 px-5 py-2 text-sm font-medium text-white transition hover:bg-blue-600 disabled:cursor-not-allowed disabled:opacity-40"
                >
                  {updateStatus === "loading" ? "Updating..." : "Update situation"}
                </button>
              </div>
            </form>
          )}

          {/* ── 6. Original situation (collapsed by default) ─ */}
          <OriginalSituation scenario={scenario} centralStatement={graph?.centralStatement} />

          {/* ── 7. Developer details (collapsed by default) ── */}
          {(status === "success" || status === "error") && graph && (
            <DeveloperDetails
              graph={graph}
              selectedQuestion={selectedQ}
              diagnostics={diagnostics}
              newlySurfacedNodeIds={newlySurfacedNodeIds}
              updateResult={updateStatus === "success" ? result : null}
            />
          )}

          {/* ── Terminal state with understanding (when no active question) ─ */}
          {status === "success" && !canAnswer && graph && genuineCompletion && <CurrentUnderstandingCard currentSummary={graph.currentSummary} />}
          {status === "success" && !canAnswer && graph && !genuineCompletion && updateStatus !== "success" && <CurrentUnderstandingCard currentSummary={graph.currentSummary} />}
        </>
      )}

      {/* ── Errors (always visible above debug) ─────────── */}
      {(status === "error" || updateStatus === "error") && (
        <div className="space-y-3">
          {status === "error" && 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>
          )}
          {updateStatus === "error" && result?.updateError && (
            <div className="rounded-lg border border-red-300 bg-red-50 px-4 py-3 text-sm text-red-700">
              Update error: {result.updateError.error || JSON.stringify(result.updateError)}
            </div>
          )}
        </div>
      )}
    </div>
  );
}

export { useLoadingStatus, INITIAL_MESSAGES, UPDATE_MESSAGES, LoadingOverlay, resolveCurrentSummary, isTechnicalSummary };