/**
 * ProposalController — the editor-facing layer for F4 (spec
 * coauthoring-propose-accept §6.2). Owns the proposal lifecycle: the propose
 * ingress (INV-10: NEVER mutates the document), persistence at propose time,
 * resolve-or-flag on load/external change (INV-11 — a proposal's anchor is
 * immutable for its life: no save-time re-fingerprint, unlike threads),
 * anchor bookkeeping into state.live/state.unresolved (no in-editor UI —
 * F10/INV-32 makes the rendered preview the single review surface),
 * and the human-only accept/reject gestures (INV-12). Accept drives the seam
 * (AttributionController.applyAgentEdit, INV-9) so accepted text lands
 * Claude-attributed with zero new attribution code.
 */
import * as vscode from "vscode";
import { SidecarRouter, docIdentity } from "./sidecarRouter";
import { emptyArtifact, type Artifact, type Fingerprint, type Proposal, type Provenance } from "./model";
import { resolve, shift, type OffsetRange } from "./anchorer";
import { addProposal, removeProposal } from "./proposalModel";
import type { AttributionController } from "./attributionController";
import type { VersionGuard } from "./versionGuard";
import { isAuthorable } from "./workspacePath";
import type { ProposalView } from "./trackChangesModel";

/** Test-facing snapshot of what is currently rendered for a document. */
export interface RenderedProposal {
  id: string;
  /** true → resolves exactly, decidable; false → stale/orphaned (INV-11). */
  pending: boolean;
  /** always false — proposals are decide-only, no reply input (INV-12). */
  canReply: boolean;
  turnId?: string;
  range: { start: number; end: number };
}

interface DocState {
  docPath: string;
  uri: vscode.Uri;
  artifact: Artifact;
  /** proposal id -> live offset range (within-session optimization, INV-3). */
  live: Map<string, OffsetRange>;
  /** proposal ids whose anchor did not resolve at last render (stale/orphaned). */
  unresolved: Set<string>;
}

export class ProposalController implements vscode.Disposable {
  private readonly disposables: vscode.Disposable[] = [];
  private readonly docs = new Map<string, DocState>(); // keyed by docPath
  private readonly statusItem = vscode.window.createStatusBarItem(vscode.StatusBarAlignment.Right, 89);
  private readonly onDidChangeProposalsEmitter = new vscode.EventEmitter<{ uri: string }>();
  /** Fires on propose / accept / reject / external sidecar change (F10). */
  readonly onDidChangeProposals = this.onDidChangeProposalsEmitter.event;

  constructor(
    private readonly store: SidecarRouter,
    private readonly attribution: AttributionController,
    private readonly rootDir: string | undefined,
    private readonly guard: VersionGuard,
  ) {
    this.disposables.push(this.statusItem);
    this.disposables.push(this.onDidChangeProposalsEmitter);
    this.disposables.push(
      vscode.workspace.onDidChangeTextDocument((e) => this.onDidChange(e)),
    );
  }

  private fireChanged(document: vscode.TextDocument): void {
    this.onDidChangeProposalsEmitter.fire({ uri: document.uri.toString() });
  }

  private isTracked(document: vscode.TextDocument): boolean {
    return isAuthorable(document.uri.scheme);
  }
  /** The single document key (F8): repo-relative path in-workspace, URI string otherwise. */
  private keyOf(document: vscode.TextDocument): string {
    return this.store.keyOf(docIdentity(document));
  }
  /** The doc key F4 uses (F8 routing) — exposed for F10's preview. */
  keyFor(document: vscode.TextDocument): string {
    return this.keyOf(document);
  }
  /** Resolved proposal views for the F10 preview (anchorStart=null when unresolved). */
  listProposals(document: vscode.TextDocument): ProposalView[] {
    const docPath = this.keyOf(document);
    const artifact = this.store.load(docPath) ?? emptyArtifact(docPath);
    const text = document.getText();
    return artifact.proposals.map((p) => {
      const fp = artifact.anchors[p.anchorId]?.fingerprint;
      const resolved = fp ? resolve(text, fp) : "orphaned";
      return {
        id: p.id,
        anchorStart: resolved === "orphaned" ? null : resolved.start,
        anchorEnd: resolved === "orphaned" ? null : resolved.end,
        replaced: fp?.text ?? "",
        replacement: p.replacement,
      };
    });
  }
  private ensureState(document: vscode.TextDocument): DocState {
    const docPath = this.keyOf(document);
    let state = this.docs.get(docPath);
    if (!state) {
      state = {
        docPath,
        uri: document.uri,
        artifact: this.store.load(docPath) ?? emptyArtifact(docPath),
        live: new Map(),
        unresolved: new Set(),
      };
      this.docs.set(docPath, state);
    }
    return state;
  }

  // ---- PUC-1: the propose ingress (INV-10) -----------------------------------------

  /**
   * Record + render a pending proposal. The fingerprint is built by the CALLER
   * at gesture time (editSelection captures it BEFORE the turn, so mid-turn
   * edits can't skew the anchor). Never touches the document.
   */
  async propose(
    document: vscode.TextDocument,
    fp: Fingerprint,
    replacement: string,
    author: Provenance,
    opts?: { turnId?: string; instruction?: string },
  ): Promise<string | undefined> {
    if (!this.isTracked(document)) return undefined;
    if (this.guard.isReadOnly(this.keyOf(document))) return undefined;
    const docPath = this.keyOf(document);
    let proposalId: string | undefined;
    this.store.update(docPath, (a) => {
      proposalId = addProposal(a, fp, replacement, author, opts).proposalId;
    });
    this.renderAll(document);
    return proposalId;
  }

  // ---- PUC-2/PUC-3: accept / reject (INV-11/INV-12) ----------------------------------

  /** Accept by proposal id (test-facing twin of the thread-menu gesture). */
  async acceptById(docPath: string, proposalId: string): Promise<boolean> {
    const hit = this.byId(docPath, proposalId);
    return hit ? this.accept(hit.state, hit.proposal) : false;
  }
  /** Reject by proposal id (test-facing twin of the thread-menu gesture). */
  rejectById(docPath: string, proposalId: string): boolean {
    const hit = this.byId(docPath, proposalId);
    if (!hit) return false;
    this.reject(hit.state, hit.proposal);
    return true;
  }

  private async accept(state: DocState, proposal: Proposal): Promise<boolean> {
    if (this.guard.isReadOnly(state.docPath)) return false;
    const document = this.openDoc(state);
    if (!document) return false;
    // INV-11: the fingerprint-guard — exact re-resolve at decision time.
    const fp = state.artifact.anchors[proposal.anchorId]?.fingerprint;
    const resolved = fp ? resolve(document.getText(), fp) : "orphaned";
    if (resolved === "orphaned") {
      void vscode.window.showWarningMessage(
        "Cowriting: this proposal's target text changed or is missing — undo to restore it, or reject to discard (it is never applied by guess).",
      );
      this.renderAll(document);
      return false;
    }
    const range = new vscode.Range(document.positionAt(resolved.start), document.positionAt(resolved.end));
    // No awaits between resolve and the seam call: document.version is current.
    const ok = await this.attribution.applyAgentEdit(document, range, proposal.replacement, proposal.author, {
      expectedVersion: document.version,
      turnId: proposal.turnId,
    });
    if (!ok) {
      void vscode.window.showWarningMessage(
        "Cowriting: the editor rejected the accept — the proposal is still pending.",
      );
      return false;
    }
    this.store.update(state.docPath, (a) => removeProposal(a, proposal.id));
    this.renderAll(document);
    return true;
  }

  private reject(state: DocState, proposal: Proposal): void {
    if (this.guard.isReadOnly(state.docPath)) return;
    this.store.update(state.docPath, (a) => removeProposal(a, proposal.id));
    const document = this.openDoc(state);
    if (document) this.renderAll(document);
  }

  // ---- PUC-4: load / external change / resolve-or-flag --------------------------------

  /** Load + (re)render every pending proposal at its resolved anchor (or flagged). */
  renderAll(document: vscode.TextDocument): void {
    if (!this.isTracked(document)) return;
    const docPath = this.keyOf(document);
    const state = this.ensureState(document);
    state.artifact = this.store.load(docPath) ?? emptyArtifact(docPath);
    state.live.clear();
    state.unresolved.clear();
    const text = document.getText();
    for (const proposal of state.artifact.proposals) {
      const fp = state.artifact.anchors[proposal.anchorId]?.fingerprint;
      const resolved = fp ? resolve(text, fp) : "orphaned";
      if (resolved === "orphaned") {
        const line = fp ? Math.min(fp.lineHint, Math.max(0, document.lineCount - 1)) : 0;
        const off = document.offsetAt(new vscode.Position(line, 0));
        this.recordProposal(state, proposal, { start: off, end: off }, false);
      } else {
        this.recordProposal(state, proposal, resolved, true);
      }
    }
    this.renderStatus(state);
    this.fireChanged(document);
  }

  /** Shared-watcher entry point (extension.ts): a sidecar changed externally. */
  handleExternalSidecarChange(uri: vscode.Uri): void {
    for (const state of this.docs.values()) {
      if (this.store.sidecarPath(state.docPath) === uri.fsPath) {
        const doc = vscode.workspace.textDocuments.find((d) => this.keyOf(d) === state.docPath);
        if (doc) this.renderAll(doc);
      }
    }
  }

  private onDidChange(e: vscode.TextDocumentChangeEvent): void {
    const state = this.docs.get(this.keyOf(e.document));
    if (!state || state.live.size === 0) return;
    for (const change of e.contentChanges) {
      const edit = { start: change.rangeOffset, end: change.rangeOffset + change.rangeLength, newLength: change.text.length };
      for (const [id, range] of state.live) state.live.set(id, shift(range, edit));
    }
  }

  // ---- rendering -----------------------------------------------------------------------

  /**
   * Record a proposal's resolved anchor in the live/unresolved bookkeeping.
   * No editor UI (F10/INV-32: the rendered preview is the single review
   * surface) — this keeps state.live/state.unresolved populated so the preview
   * (SLICE-3) and the getRendered test seam can read it.
   */
  private recordProposal(state: DocState, proposal: Proposal, offsets: OffsetRange, pending: boolean): void {
    state.live.set(proposal.id, offsets);
    if (!pending) state.unresolved.add(proposal.id);
  }

  private renderStatus(state: DocState): void {
    const n = state.unresolved.size;
    if (n === 0) {
      this.statusItem.hide();
      return;
    }
    this.statusItem.text = `$(warning) ${n} stale proposal${n === 1 ? "" : "s"}`;
    this.statusItem.tooltip =
      "Cowriting: proposals whose target text changed or is missing — undo to restore, or reject";
    this.statusItem.show();
  }

  // ---- lookups ----------------------------------------------------------------------------

  private openDoc(state: DocState): vscode.TextDocument | undefined {
    return vscode.workspace.textDocuments.find((d) => this.keyOf(d) === state.docPath);
  }
  private byId(docPath: string, proposalId: string): { state: DocState; proposal: Proposal } | undefined {
    const state = this.docs.get(docPath);
    const proposal = state?.artifact.proposals.find((p) => p.id === proposalId);
    return state && proposal ? { state, proposal } : undefined;
  }

  // ---- test-facing surface ------------------------------------------------------------------

  getRendered(docPath: string): RenderedProposal[] {
    const state = this.docs.get(docPath);
    if (!state) return [];
    const out: RenderedProposal[] = [];
    for (const [id, off] of state.live) {
      const p = state.artifact.proposals.find((x) => x.id === id)!;
      out.push({ id, pending: !state.unresolved.has(id), canReply: false, turnId: p.turnId, range: { start: off.start, end: off.end } });
    }
    return out;
  }
  getStaleCount(docPath: string): number {
    return this.docs.get(docPath)?.unresolved.size ?? 0;
  }

  dispose(): void {
    for (const d of this.disposables) d.dispose();
  }
}