/**
 * EditorProposalController — F12/#64 editor surface (spec coauthoring-inline-editor-diff
 * §3.5). Reverses INV-32 for pending proposals: on `onDidChangeProposals` it
 * (1) optimistically applies any not-yet-applied proposal into the active editor's
 * buffer (ProposalController.optimisticApply, INV-48), (2) decorates each applied
 * proposal — insertion tint over the proposed text + a non-editable struck-red hint
 * for deletions (INV-52, decorationPlan/INV-49), and (3) provides a CodeLens
 * `Accept ▾ / Reject ▾` above each block whose ▾ opens a QuickPick (this / all).
 * Owns no proposal STATE — it is a view over ProposalController (which stays the
 * pure F4 owner). A document with no pending proposals shows nothing (INV-32's
 * spirit when nothing is pending).
 */
import * as vscode from "vscode";
import type { ProposalController } from "./proposalController";
import { decorationPlan } from "./trackChangesModel";
import { isAuthorable } from "./workspacePath";

export class EditorProposalController implements vscode.Disposable, vscode.CodeLensProvider {
  private readonly disposables: vscode.Disposable[] = [];
  private readonly insertionDeco = vscode.window.createTextEditorDecorationType({
    backgroundColor: new vscode.ThemeColor("diffEditor.insertedTextBackground"),
  });
  private readonly deletionDeco = vscode.window.createTextEditorDecorationType({
    // a non-editable struck-red hint injected AFTER the insertion (INV-52)
    after: { color: new vscode.ThemeColor("gitDecoration.deletedResourceForeground") },
    textDecoration: "none",
  });
  private readonly lensEmitter = new vscode.EventEmitter<void>();
  readonly onDidChangeCodeLenses = this.lensEmitter.event;
  /** Pending debounce timers — one per URI — coalesce rapid-fire propose events
   * (e.g. runEditAndPropose's N sequential propose() calls) into a single
   * optimistic-apply pass that runs after ALL proposals are created. Without this,
   * each propose() fires onDidChangeProposals synchronously and the controller's
   * optimisticApply runs concurrently with the still-in-progress propose loop,
   * causing "file changed in the meantime" workspace-edit conflicts. */
  private readonly pendingApply = new Map<string, ReturnType<typeof setTimeout>>();

  constructor(private readonly proposals: ProposalController) {
    this.disposables.push(
      this.insertionDeco, this.deletionDeco, this.lensEmitter,
      vscode.languages.registerCodeLensProvider({ language: "markdown" }, this),
      this.proposals.onDidChangeProposals(({ uri }) => this.scheduleApply(uri)),
      vscode.window.onDidChangeActiveTextEditor((ed) => ed && this.renderEditor(ed)),
      // the four QuickPick-backed menu commands
      vscode.commands.registerCommand("cowriting.proposalAcceptMenu", (id?: string) => this.menu("accept", id)),
      vscode.commands.registerCommand("cowriting.proposalRejectMenu", (id?: string) => this.menu("reject", id)),
    );
  }

  /** Debounce-schedule an optimistic-apply pass for the given URI. Multiple rapid
   * onDidChangeProposals events (from a single runEditAndPropose batch) collapse
   * into one pass that runs after the batch completes. */
  private scheduleApply(uri: string): void {
    const prev = this.pendingApply.get(uri);
    if (prev !== undefined) clearTimeout(prev);
    this.pendingApply.set(
      uri,
      setTimeout(() => {
        this.pendingApply.delete(uri);
        void this.onProposalsChanged(uri);
      }, 0),
    );
  }

  /** Apply any not-yet-applied proposals on the doc, then re-decorate + refresh lenses. */
  private async onProposalsChanged(uri: string): Promise<void> {
    const doc = vscode.workspace.textDocuments.find((d) => d.uri.toString() === uri);
    if (!doc || doc.languageId !== "markdown" || !isAuthorable(doc.uri.scheme)) return;
    const key = this.proposals.keyFor(doc);
    for (const v of this.proposals.listProposals(doc)) {
      if (v.anchorStart !== null && !this.proposals.isApplied(key, v.id)) {
        await this.proposals.optimisticApply(doc, v.id); // fires onDidChangeProposals again; guarded by isApplied
      }
    }
    const ed = vscode.window.visibleTextEditors.find((e) => e.document.uri.toString() === uri);
    if (ed) this.renderEditor(ed);
    this.lensEmitter.fire();
  }

  /** Decorate the editor for every applied proposal on its document (INV-52). */
  private renderEditor(editor: vscode.TextEditor): void {
    const doc = editor.document;
    if (doc.languageId !== "markdown") {
      editor.setDecorations(this.insertionDeco, []);
      editor.setDecorations(this.deletionDeco, []);
      return;
    }
    const key = this.proposals.keyFor(doc);
    const insertions: vscode.Range[] = [];
    const deletions: vscode.DecorationOptions[] = [];
    for (const v of this.proposals.listProposals(doc)) {
      if (v.anchorStart === null || v.original === undefined || !this.proposals.isApplied(key, v.id)) continue;
      const plan = decorationPlan(v.anchorStart, v.original, v.replacement);
      for (const ins of plan.insertions) {
        insertions.push(new vscode.Range(doc.positionAt(ins.start), doc.positionAt(ins.end)));
      }
      for (const del of plan.deletions) {
        deletions.push({
          range: new vscode.Range(doc.positionAt(del.at), doc.positionAt(del.at)),
          renderOptions: { after: { contentText: ` ${del.text} `, textDecoration: "line-through" } },
        });
      }
    }
    editor.setDecorations(this.insertionDeco, insertions);
    editor.setDecorations(this.deletionDeco, deletions);
  }

  /** CodeLensProvider: a `Accept ▾` / `Reject ▾` pair above each applied block. */
  provideCodeLenses(document: vscode.TextDocument): vscode.CodeLens[] {
    if (document.languageId !== "markdown") return [];
    const key = this.proposals.keyFor(document);
    const lenses: vscode.CodeLens[] = [];
    for (const v of this.proposals.listProposals(document)) {
      if (v.anchorStart === null || !this.proposals.isApplied(key, v.id)) continue;
      const pos = document.positionAt(v.anchorStart);
      const line = new vscode.Range(pos.line, 0, pos.line, 0);
      lenses.push(
        new vscode.CodeLens(line, { title: "Accept ▾", command: "cowriting.proposalAcceptMenu", arguments: [v.id] }),
        new vscode.CodeLens(line, { title: "Reject ▾", command: "cowriting.proposalRejectMenu", arguments: [v.id] }),
      );
    }
    return lenses;
  }

  /** The dropdown: this-proposal vs all-proposals, then dispatch. */
  private async menu(kind: "accept" | "reject", id?: string): Promise<void> {
    const doc = vscode.window.activeTextEditor?.document;
    if (!doc || !id) return;
    const key = this.proposals.keyFor(doc);
    const verb = kind === "accept" ? "Accept" : "Reject";
    const pick = await vscode.window.showQuickPick(
      [`${verb} this proposal`, `${verb} ALL proposals`],
      { placeHolder: `${verb} Claude's proposal` },
    );
    if (!pick) return;
    const all = pick.includes("ALL");
    if (kind === "accept") {
      if (all) await this.proposals.acceptAllProposals(doc);
      else await this.proposals.finalizeInPlace(key, id);
    } else {
      if (all) await this.proposals.rejectAll(doc);
      else await this.proposals.revertInPlace(key, id);
    }
  }

  dispose(): void {
    for (const t of this.pendingApply.values()) clearTimeout(t);
    this.pendingApply.clear();
    for (const d of this.disposables) d.dispose();
  }
}