"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" }}
    />
  );
}

// ── Situation card ────────────────────────────────────────────
function SituationCard({ centralStatement }) {
  if (!centralStatement) return null;
  return (
    <div className="investigation-card rounded-lg border border-gray-200 bg-white p-5">
      <h2 className="mb-2 text-sm font-semibold uppercase tracking-wide text-gray-500">
        Your situation
      </h2>
      <p className="text-base leading-relaxed text-gray-900">{centralStatement}</p>
    </div>
  );
}

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

  return (
    <div className="investigation-card rounded-lg border border-gray-200 bg-white p-5">
      <h2 className="mb-3 text-sm font-semibold uppercase tracking-wide text-gray-500">
        What we&#x27;ve established
      </h2>
      {summary ? (
        <p className="text-sm leading-relaxed text-gray-700">{summary}</p>
      ) : (
        <p className="text-sm leading-relaxed text-gray-600">
          We have separated what is known from what still needs checking.
        </p>
      )}
    </div>
  );
}

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

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

  return (
    <div className="investigation-card rounded-lg border-2 border-green-300 bg-green-50 p-6 transition-opacity duration-300">
      <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>
    </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;
}

// ── Investigation progress card ──────────────────────────────
function InvestigationProgress({ graph, noQuestionReason: rwNoQuestionReason }) {
  if (!graph?.nodes?.length) return null;

  const resolvedIds = new Set(graph.resolvedNodeIds || []);
  const unknowns = graph.nodes.filter((n) => n.kind === "unknown");
  const remainingCount = unknowns.filter(
    (u) => u.status !== "resolved" && !resolvedIds.has(u.id),
  ).length;
  const activeNode = graph.activeUnknownNodeId
    ? graph.nodes.find((n) => n.id === graph.activeUnknownNodeId)
    : null;

  const isComplete = hasGenuineCompletion(graph);

  return (
    <div className="investigation-card rounded-lg border border-gray-200 bg-white px-5 py-4">
      {remainingCount > 0 && !isComplete ? (
        <p className="text-sm leading-relaxed text-gray-700">
          We are still building confidence about your situation.{" "}
          {remainingCount === 1
            ? "One area remains."
            : `${remainingCount} areas remain.`}
        </p>
      ) : (
        <p className="text-sm leading-relaxed text-gray-700">
          All areas under investigation are now complete.
        </p>
      )}
      {activeNode && (
        <>
          <h3 className="mt-3 mb-1 text-xs font-medium uppercase tracking-wide text-gray-400">
            Current focus
          </h3>
          <p className="text-sm font-medium text-gray-900">{activeNode.label}</p>
          {activeNode.description && activeNode.description !== activeNode.label && (
            <p className="mt-1 text-xs text-gray-500">Why it matters: {activeNode.description}</p>
          )}
        </>
      )}
      {!activeNode && remainingCount === 0 && (
        <p className="mt-3 text-sm text-gray-500">There is nothing further to investigate at this time.</p>
      )}
    </div>
  );
}

// ── Investigation complete state ───────────────────────────────
function InvestigationCompleteMessage({ noQuestionReason }) {
  let message = "We have established enough for now.";
  if (noQuestionReason) {
    const reason = String(noQuestionReason);
    if (
      reason.toLowerCase().includes("resolved") ||
      reason.toLowerCase().includes("satisfied") ||
      reason.toLowerCase().includes("complete")
    ) {
      message = "You have provided enough information. The situation has been fully investigated.";
    } else if (reason.toLowerCase().includes("insufficient")) {
      message = "There is not yet enough evidence to guide the next step. Your original situation will remain our focus when new information becomes available.";
    } else {
      message = reason;
    }
  }
  return (
    <div className="rounded-lg border border-gray-200 bg-gray-50 px-5 py-4 text-center transition-opacity duration-300">
      <p className="text-sm text-gray-600">{message}</p>
    </div>
  );
}

// ── 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>
  );
}

// ── Update acknowledgement ────────────────────────────────────
function UpdateAcknowledgement({ answer, updateResult }) {
  if (!updateResult || !answer?.trim()) return null;

  const hasResolvedNodes =
    updateResult.resolvedUnknownNodeIds && updateResult.resolvedUnknownNodeIds.length > 0;
  const hasAffectedNodes =
    updateResult.affectedNodeIds && 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 || hasAffectedNodes) {
    const items = [];
    if (hasResolvedNodes) {
      for (const id of updateResult.resolvedUnknownNodeIds.slice(0, 5)) {
        items.push(getNodeText(id));
      }
      if (updateResult.resolvedUnknownNodeIds.length > 5) {
        items.push(`and ${updateResult.resolvedUnknownNodeIds.length - 5} more resolved`);
      }
    }
    if (hasAffectedNodes && !hasResolvedNodes) {
      for (const id of updateResult.affectedNodeIds.slice(0, 5)) {
        items.push(getNodeText(id));
      }
      if (updateResult.affectedNodeIds.length > 5) {
        items.push(`and ${updateResult.affectedNodeIds.length - 5} more affected`);
      }
    }
    if (items.length === 0 && updateResult.changesApplied) {
      const parts = [];
      const ca = updateResult.changesApplied;
      if (ca.addedNodeCount) parts.push(`${ca.addedNodeCount} node(s) added`);
      if (ca.updatedNodeCount) parts.push(`${ca.updatedNodeCount} node(s) updated`);
      if (ca.resolvedUnknownCount) parts.push(`${ca.resolvedUnknownCount} unknown(s) resolved`);
      changedText = parts.join(", ");
    } else {
      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 summary = updateResult.summary || null;
  const displayChanged = summary || changedText || "Your answer has been added to the investigation.";

  return (
    <div className="rounded-lg border border-blue-200 bg-blue-50 px-5 py-4 space-y-3">
      <div>
        <h3 className="mb-1 text-xs font-medium uppercase tracking-wide text-blue-700">
          You told us
        </h3>
        <p className="text-sm leading-relaxed text-blue-900">{answer}</p>
      </div>
      <div>
        <h3 className="mb-1 text-xs font-medium uppercase tracking-wide text-blue-700">
          What changed
        </h3>
        <p className="text-sm leading-relaxed text-blue-900">{displayChanged}</p>
      </div>
    </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>
  );
}

// ── Main workspace component ──────────────────────────────────
export default function ReasoningWorkspace({
  status,
  updateStatus,
  result,
  answer,
  setAnswer,
  onAnswerSubmit,
  lastSubmittedAnswer,
}) {
  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 remainingUnknowns = graph?.nodes?.filter(
    (n) => n.kind === "unknown" && n.status !== "resolved" && !(graph.resolvedNodeIds || []).includes(n.id),
  );

  const genuineCompletion = hasGenuineCompletion(graph);
  const unresolvedRemaining = !genuineCompletion && remainingUnknowns ? remainingUnknowns.length > 0 : false;

  return (
    <div className="space-y-5">
      {/* ── Loading overlays ─────────────────────────────── */}
      <LoadingOverlay
        isLoading={status === "loading"}
        elapsed={startElapsed}
        currentMessage={startMsg}
        variant="initial"
      />
      {updateStatus === "loading" && (
        <div className="h-px bg-gray-100" />
      )}
      <LoadingOverlay
        isLoading={updateStatus === "loading"}
        elapsed={updateElapsed}
        currentMessage={updateMsg}
        variant="update"
      />

      {/* ── User-facing workspace ────────────────────────── */}
      {(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>
      ) : (
        <>
          {/* ── Post-update acknowledgement ─────────────── */}
          {updateStatus === "success" && graph && (
            <UpdateAcknowledgement answer={lastSubmittedAnswer} updateResult={result} />
          )}

          {/* Completion state (only when there is no next question and nothing remains) */}
          {status === "success" && !canAnswer && graph && genuineCompletion && (
            <InvestigationCompleteMessage noQuestionReason={noQuestionReason} />
          )}
          {status === "success" && !canAnswer && graph && unresolvedRemaining && updateStatus !== "success" && (
            <div className="rounded-lg border border-gray-200 bg-gray-50 px-5 py-4 text-center">
              <p className="text-sm text-gray-600">There is no further question the engine can justify at the moment.</p>
              <p className="mt-1 text-xs text-gray-500">More evidence may be needed before a next step is clear.</p>
            </div>
          )}

          {graph && <SituationCard centralStatement={graph.centralStatement} />}
          {graph && <CurrentUnderstanding currentSummary={graph.currentSummary} />}
          {canAnswer && <CurrentInvestigationCard selectedQuestion={selectedQ} />}
          {graph && <InvestigationProgress graph={graph} noQuestionReason={noQuestionReason} />}

          {/* ── Answer form ──────────────────────────────── */}
          {canAnswer && (
            <form onSubmit={onAnswerSubmit} 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>
          )}

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

      {/* ── 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 };