import { useEffect, useMemo, useState } from "react";

import type { CapabilityDevtoolsSnapshot } from "../../../src/devtools";
import { Icon, type IconName } from "./Icons";
import { EvalAssertions, type EvalAssertion } from "./ThreadItems";

export type CapabilityDevtoolsTab = "eval" | "evidence" | "timeline" | "state" | "diff" | "documents" | "protocol" | "runtime" | "authority";
type Json = null | boolean | number | string | Json[] | { [key: string]: Json };

export interface EvalInspectorReport {
  attemptId: string;
  caseId: string;
  disposition: string;
  passed: boolean;
  checks: EvalAssertion[];
  run: { model: string; provider: string; configuration: string; sessionId: string; fixtureDigest: string; runnerPackageDigest: string; runnerdDigest: string; runnerBuild: string; startedAt: string; finishedAt: string; durationMs: number; initialRevision: number; finalRevision: number; usage: { agentTurns: number; providerRequests: number | null; inputTokens: number; outputTokens: number; cachedInputTokens: number; reasoningTokens: number; estimatedCostNanodollars: number; pricingVersion: string } | null };
}

function JsonTree({ value, name = "root" }: { value: Json; name?: string }) {
  if (value === null || typeof value !== "object") {
    return <span className="pit-json-value">{JSON.stringify(value)}</span>;
  }
  const entries = Array.isArray(value)
    ? value.map((entry, index) => [String(index), entry] as const)
    : Object.entries(value);
  return (
    <details className="pit-json-node" open={name === "root"}>
      <summary>{name} <span className="pit-muted">{Array.isArray(value) ? `[${entries.length}]` : `{${entries.length}}`}</span></summary>
      <div className="pit-json-children">
        {entries.map(([key, entry]) => (
          <div className="pit-json-row" key={key}>
            <span className="pit-json-key">{key}</span>
            {entry !== null && typeof entry === "object"
              ? <JsonTree value={entry as Json} name={key} />
              : <JsonTree value={entry as Json} />}
          </div>
        ))}
      </div>
    </details>
  );
}

interface DiffRow { path: string; before: Json | undefined; after: Json | undefined }

function diff(before: Json | undefined, after: Json | undefined, path = "state"): DiffRow[] {
  if (JSON.stringify(before) === JSON.stringify(after)) return [];
  if (
    before !== null && after !== null &&
    typeof before === "object" && typeof after === "object" &&
    !Array.isArray(before) && !Array.isArray(after)
  ) {
    const keys = new Set([...Object.keys(before), ...Object.keys(after)]);
    return [...keys].flatMap((key) => diff(before[key], after[key], `${path}.${key}`));
  }
  return [{ path, before, after }];
}

function download(snapshot: CapabilityDevtoolsSnapshot) {
  const blob = new Blob([JSON.stringify(snapshot, null, 2)], { type: "application/json" });
  const url = URL.createObjectURL(blob);
  const anchor = document.createElement("a");
  anchor.href = url;
  anchor.download = `paperclip-devtools-r${snapshot.currentRevision}.json`;
  anchor.click();
  URL.revokeObjectURL(url);
}

const TABS: ReadonlyArray<{ id: CapabilityDevtoolsTab; icon: IconName; label: string }> = [
  { id: "evidence", icon: "evidence", label: "Evidence" },
  { id: "timeline", icon: "timeline", label: "Timeline" },
  { id: "state", icon: "state", label: "State" },
  { id: "diff", icon: "diff", label: "Diff" },
  { id: "documents", icon: "documents", label: "Documents" },
  { id: "protocol", icon: "protocol", label: "Protocol" },
  { id: "runtime", icon: "terminal", label: "Runtime" },
  { id: "authority", icon: "authority", label: "Authority" },
];

function documentsOf(state: Json): Array<{ id: string; key: string; title: string; revisions: Array<{ id: string; revision: number; body: string; changeSummary: string | null; createdAt: string }> }> {
  if (state === null || typeof state !== "object" || Array.isArray(state)) return [];
  const documents = state.documents;
  if (!Array.isArray(documents)) return [];
  return documents.flatMap((value) => {
    if (value === null || typeof value !== "object" || Array.isArray(value)) return [];
    const revisions = Array.isArray(value.revisions) ? value.revisions.flatMap((candidate) => {
      if (candidate === null || typeof candidate !== "object" || Array.isArray(candidate)) return [];
      return [{
        id: String(candidate.id ?? ""),
        revision: Number(candidate.revision ?? 0),
        body: String(candidate.body ?? ""),
        changeSummary: candidate.changeSummary === null ? null : String(candidate.changeSummary ?? ""),
        createdAt: String(candidate.createdAt ?? ""),
      }];
    }) : [];
    return [{ id: String(value.id ?? ""), key: String(value.key ?? ""), title: String(value.title ?? "Untitled"), revisions }];
  });
}

export function DevtoolsInspector({ snapshot, onFork, tab, onTabChange, evalReport }: { snapshot: CapabilityDevtoolsSnapshot; onFork: (revision: number) => void; tab: CapabilityDevtoolsTab; onTabChange: (tab: CapabilityDevtoolsTab) => void; evalReport?: EvalInspectorReport | null }) {
  const [query, setQuery] = useState("");
  const latest = snapshot.revisions.at(-1)!;
  const [revision, setRevision] = useState(latest.revision);
  const [following, setFollowing] = useState(true);
  const [compareRevision, setCompareRevision] = useState(snapshot.revisions[0]!.revision);
  const selected = snapshot.revisions.find((entry) => entry.revision === revision) ?? latest;
  const compared = snapshot.revisions.find((entry) => entry.revision === compareRevision) ?? snapshot.revisions[0]!;
  const rows = useMemo(
    () => diff(compared.state as Json, selected.state as Json),
    [compared.state, selected.state],
  );
  const normalized = query.trim().toLowerCase();
  const revisions = snapshot.revisions.filter((entry) =>
    normalized.length === 0 || JSON.stringify(entry).toLowerCase().includes(normalized),
  );
  const protocol = snapshot.protocol.filter((entry) =>
    normalized.length === 0 || JSON.stringify(entry).toLowerCase().includes(normalized),
  );
  const documents = useMemo(() => documentsOf(selected.state as Json), [selected.state]);
  const [documentId, setDocumentId] = useState("");
  const document = documents.find((entry) => entry.id === documentId) ?? documents[0] ?? null;
  const [documentRevision, setDocumentRevision] = useState(0);
  const visibleDocumentRevision = document?.revisions.find((entry) => entry.revision === documentRevision) ?? document?.revisions.at(-1) ?? null;
  useEffect(() => {
    if (following) setRevision(latest.revision);
  }, [following, latest.revision]);

  return (
    <section className="pit-devtools" data-testid="devtools-inspector">
      <div className="pit-devtools-toolbar">
        <span className="pit-devtools-brand"><Icon name="activity" /> State monitor</span>
        <input id="devtools-search" className="pit-input" value={query} onChange={(event) => setQuery(event.target.value)} placeholder="operation, entity, turn…" />
        <button className="pit-icon-button" type="button" aria-pressed={!following} onClick={() => setFollowing((value) => !value)} title={following ? "Pause live updates" : "Follow latest revision"} aria-label={following ? "Pause live updates" : "Follow latest revision"}><Icon name={following ? "pause" : "play"} /></button>
        <button className="pit-icon-button" type="button" onClick={() => download(snapshot)} title="Export redacted snapshot" aria-label="Export redacted snapshot"><Icon name="download" /></button>
        <button className="pit-button" type="button" onClick={() => onFork(revision)}><Icon name="branch" /> Fork r{revision}</button>
      </div>
      <div className="pit-devtools-tabs" role="tablist" aria-label="Developer tools">
        {([...(evalReport ? [{ id: "eval" as const, icon: "evidence" as const, label: "Eval" }] : []), ...TABS]).map(({ id, icon, label }) => (
          <button key={id} type="button" role="tab" aria-selected={tab === id} className="pit-tab" onClick={() => onTabChange(id)}><span className="pit-tab-glyph"><Icon name={icon} /></span><span>{label}</span></button>
        ))}
      </div>
      {tab === "eval" && evalReport ? (
        <div className="pit-devtools-pane pit-eval-inspector">
          <div className="pit-eval-summary-head"><a href="../../index.html">← Eval suite</a><strong>{evalReport.passed ? "PASS" : evalReport.disposition.replaceAll("_", " ").toUpperCase()}</strong><code>{evalReport.attemptId}</code></div>
          <dl className="pit-eval-run-facts">
            <div><dt>Model</dt><dd>{evalReport.run.provider}/{evalReport.run.model}</dd></div>
            <div><dt>Configuration</dt><dd>{evalReport.run.configuration}</dd></div>
            <div><dt>Session</dt><dd>{evalReport.run.sessionId}</dd></div>
            <div><dt>Duration</dt><dd>{evalReport.run.durationMs} ms</dd></div>
            <div><dt>Fixture</dt><dd>{evalReport.run.fixtureDigest}</dd></div>
            <div><dt>State</dt><dd>r{evalReport.run.initialRevision} → r{evalReport.run.finalRevision}</dd></div>
            <div><dt>Tokens</dt><dd>{evalReport.run.usage === null ? "unknown" : `${evalReport.run.usage.inputTokens} in · ${evalReport.run.usage.outputTokens} out · ${evalReport.run.usage.cachedInputTokens} cached`}</dd></div>
            <div><dt>Agent turns</dt><dd>{evalReport.run.usage?.agentTurns ?? "unknown"}</dd></div>
            <div><dt>Provider requests</dt><dd>{evalReport.run.usage?.providerRequests ?? "unavailable"}</dd></div>
            <div><dt>Estimated cost</dt><dd>{evalReport.run.usage === null ? "unknown" : `$${(evalReport.run.usage.estimatedCostNanodollars / 1_000_000_000).toFixed(6)} · ${evalReport.run.usage.pricingVersion}`}</dd></div>
            <div><dt>Runner</dt><dd>{evalReport.run.runnerPackageDigest}</dd></div>
            <div><dt>Runner build</dt><dd>{evalReport.run.runnerBuild}</dd></div>
            <div><dt>runnerd</dt><dd>{evalReport.run.runnerdDigest}</dd></div>
          </dl>
          <h3>Assertions</h3><EvalAssertions assertions={evalReport.checks} />
        </div>
      ) : null}
      {tab === "timeline" ? (
        <div className="pit-devtools-list">
          {revisions.map((entry) => (
            <button type="button" className="pit-devtools-event" data-selected={entry.revision === revision} key={entry.revision} onClick={() => { setFollowing(false); setRevision(entry.revision); }}>
              <strong>r{entry.revision}</strong><span>{entry.operationId}</span><span className="pit-muted">{entry.turnId ?? "session"}</span>
            </button>
          ))}
        </div>
      ) : null}
      {tab === "state" ? (
        <div className="pit-devtools-pane">
          <label className="pit-card-meta" htmlFor="devtools-revision">Revision</label>
          <select id="devtools-revision" className="pit-select" value={revision} onChange={(event) => setRevision(Number(event.target.value))}>
            {snapshot.revisions.map((entry) => <option key={entry.revision} value={entry.revision}>r{entry.revision} · {entry.operationId}</option>)}
          </select>
          <JsonTree value={selected.state as Json} />
        </div>
      ) : null}
      {tab === "diff" ? (
        <div className="pit-devtools-pane">
          <div className="pit-button-row">
            <select className="pit-select" aria-label="Compare from revision" value={compareRevision} onChange={(event) => setCompareRevision(Number(event.target.value))}>
              {snapshot.revisions.map((entry) => <option key={entry.revision} value={entry.revision}>from r{entry.revision}</option>)}
            </select>
            <select className="pit-select" aria-label="Compare to revision" value={revision} onChange={(event) => setRevision(Number(event.target.value))}>
              {snapshot.revisions.map((entry) => <option key={entry.revision} value={entry.revision}>to r{entry.revision}</option>)}
            </select>
          </div>
          {rows.map((row) => <div className="pit-diff-row" key={row.path}><strong>{row.path}</strong><del>{JSON.stringify(row.before)}</del><ins>{JSON.stringify(row.after)}</ins></div>)}
          {rows.length === 0 ? <p className="pit-muted">No changes between these revisions.</p> : null}
        </div>
      ) : null}
      {tab === "documents" ? (
        documents.length === 0 ? <div className="pit-devtools-empty"><span aria-hidden="true">▤</span><p>No documents exist at r{selected.revision}.</p></div> : (
          <div className="pit-document-browser">
            <div className="pit-document-sidebar">
              {documents.map((entry) => <button type="button" key={entry.id} data-selected={entry.id === document?.id} onClick={() => { setDocumentId(entry.id); setDocumentRevision(0); }}><strong>{entry.key}</strong><span>{entry.title}</span><small>{entry.revisions.length} revision{entry.revisions.length === 1 ? "" : "s"}</small></button>)}
            </div>
            {document !== null && visibleDocumentRevision !== null ? (
              <article className="pit-document-viewer">
                <header><div><span className="pit-card-meta">{document.key}</span><h4>{document.title}</h4></div><select className="pit-select" aria-label="Document revision" value={visibleDocumentRevision.revision} onChange={(event) => setDocumentRevision(Number(event.target.value))}>{document.revisions.map((entry) => <option key={entry.id} value={entry.revision}>r{entry.revision}</option>)}</select></header>
                {visibleDocumentRevision.changeSummary ? <p className="pit-document-summary">{visibleDocumentRevision.changeSummary}</p> : null}
                <pre className="pit-document-body">{visibleDocumentRevision.body}</pre>
              </article>
            ) : null}
          </div>
        )
      ) : null}
      {tab === "protocol" ? <div className="pit-devtools-list">{protocol.map((entry) => <details className="pit-runner-event" key={entry.id}><summary><strong>{entry.boundary}</strong> · {entry.event}</summary><JsonTree value={entry.detail as Json} /></details>)}</div> : null}
      {tab === "runtime" ? <div className="pit-devtools-pane"><JsonTree value={snapshot.runtime as Json} /></div> : null}
      {tab === "authority" ? <div className="pit-devtools-pane"><JsonTree value={snapshot.authority as Json} /></div> : null}
    </section>
  );
}