// The conflict editor (spec §5.7): CodeLens actions over each conflict
// region, keep-this-candidate for tree conflicts, and mark-resolved.

import * as vscode from "vscode";
import { basename, dirname, join } from "node:path";
import { promises as fs } from "node:fs";
import { ConflictRegion, candidateBase, parseConflicts, resolveRegion } from "./markers";
import { Repository } from "./repository";

export class ConflictCodeLensProvider implements vscode.CodeLensProvider {
  private readonly emitter = new vscode.EventEmitter<void>();
  readonly onDidChangeCodeLenses = this.emitter.event;

  constructor(private readonly repositories: () => Repository[]) {}

  refresh(): void {
    this.emitter.fire();
  }

  provideCodeLenses(document: vscode.TextDocument): vscode.CodeLens[] {
    if (document.uri.scheme !== "file" || !this.repositories().some((r) => r.relativePath(document.uri) !== undefined)) {
      return [];
    }
    const text = document.getText();
    if (!text.includes("<<<<<<< oxy conflict")) {
      return [];
    }
    const regions = parseConflicts(text.split(/\r?\n/));
    const lenses: vscode.CodeLens[] = [];
    regions.forEach((region, index) => {
      const range = new vscode.Range(region.start, 0, region.start, 0);
      for (const side of region.sides) {
        const title = side.deleted ? `Accept deletion (${side.label.replace("deleted by change ", "")})` : `Accept side ${side.number} (${side.label})`;
        lenses.push(new vscode.CodeLens(range, { title, command: "oxygen.acceptSides", arguments: [document.uri, index, [side.number]] }));
      }
      if (region.sides.length > 1 && !region.sides.every((s) => s.deleted)) {
        lenses.push(new vscode.CodeLens(range, { title: "Accept all sides", command: "oxygen.acceptSides", arguments: [document.uri, index, region.sides.map((s) => s.number)] }));
      }
      lenses.push(new vscode.CodeLens(range, { title: `Conflict ${region.number} of ${region.total}`, command: "" }));
    });
    return lenses;
  }
}

/** Replace conflict region `index` of the document with the kept sides. */
export async function acceptSides(uri: vscode.Uri, index: number, keep: number[]): Promise<void> {
  const document = await vscode.workspace.openTextDocument(uri);
  const lines = document.getText().split(/\r?\n/);
  const regions = parseConflicts(lines);
  const region: ConflictRegion | undefined = regions[index];
  if (!region) {
    return;
  }
  const replacement = resolveRegion(lines, region, keep);
  const edit = new vscode.WorkspaceEdit();
  const eol = document.eol === vscode.EndOfLine.CRLF ? "\r\n" : "\n";
  const range = new vscode.Range(region.start, 0, region.end + 1, 0);
  edit.replace(uri, range, replacement.length ? replacement.join(eol) + eol : "");
  await vscode.workspace.applyEdit(edit);
  await document.save();
}

/** Keep one `.oxy-conflict-N` candidate under the real name; the others go. */
export async function keepCandidate(repo: Repository, candidatePath: string): Promise<void> {
  const base = candidateBase(candidatePath);
  if (!base) {
    return;
  }
  const dir = join(repo.root, dirname(candidatePath));
  const name = basename(base);
  const entries = await fs.readdir(dir);
  for (const e of entries) {
    if (e !== basename(candidatePath) && candidateBase(e) === name) {
      await fs.rm(join(dir, e), { recursive: true, force: true });
    }
  }
  await fs.rename(join(repo.root, candidatePath), join(repo.root, base));
  await repo.refresh();
}

export async function markResolved(repo: Repository): Promise<void> {
  const r = await repo.oxy.run(repo.root, ["resolve", "--json"]);
  await repo.refresh();
  const status = repo.status;
  if (!status || !status.conflicted) {
    void vscode.window.showInformationMessage("Oxygen: no conflicts remain.");
    return;
  }
  const unresolved = status.conflicts.filter((c) => c.resolved !== true);
  if (unresolved.length === 0) {
    void vscode.window.showInformationMessage("Oxygen: every conflict is resolved; commit to record the resolution.");
  } else {
    const names = unresolved.map((c) => `${c.path ?? c.kind}${c.resolved === "markers" ? " (markers remain)" : ""}`).join(", ");
    void vscode.window.showWarningMessage(`Oxygen: still to resolve: ${names}`);
  }
  void r;
}