// The commit box's logic (spec §5.1), kept free of the vscode module so it
// can be tested: signing state from `oxy identity show`, the placeholder
// that shows it, message history, and conflict marker detection.

export interface SigningInfo {
  /** `Name <email>`, or empty without an identity. */
  who: string;
  /** Whether the secret key is in the key directory. */
  secret: boolean;
  /** `change`: every commit is signed; `seal`: changes are sealed at push. */
  mode: "change" | "seal";
}

/** Parse `oxy --plain identity show`; `null` when no identity is configured. */
export function parseIdentityShow(text: string): SigningInfo | null {
  const head = text.match(/^#\s*identity\s+(.+)$/m);
  if (!head) {
    return null;
  }
  const secretLine = text.match(/^\s*secret\s+(.+)$/m)?.[1] ?? "";
  const signingLine = text.match(/^\s*signing\s+(.+)$/m)?.[1] ?? "";
  return {
    who: head[1].trim(),
    secret: /available/.test(secretLine),
    mode: /core\.sign\s*=\s*change/.test(signingLine) ? "change" : "seal",
  };
}

/** A short name for the placeholder: the name without the address. */
function shortName(who: string): string {
  return who.replace(/\s*<[^>]*>\s*$/, "").trim() || who;
}

/** How the next commit will be authenticated, for the commit box. */
export function signingLabel(info: SigningInfo | null | undefined): string {
  if (info === undefined) {
    return "";
  }
  if (info === null) {
    return "⚠ unsigned: no identity (oxy identity create)";
  }
  if (!info.secret) {
    return `⚠ unsigned: the key for ${shortName(info.who)} is missing`;
  }
  return info.mode === "change" ? `✔ signed as ${shortName(info.who)}` : `◈ sealed at push as ${shortName(info.who)}`;
}

/** The commit box placeholder for the current mode. */
export function placeholder(opts: { amend: boolean; resolution: boolean; signing: string }): string {
  const what = opts.amend ? "Amend the last change: new message, or empty to keep it" : opts.resolution ? "Describe the resolution" : "Message";
  const key = opts.amend ? "Ctrl+Enter to amend" : "Ctrl+Enter to commit";
  return `${what} (${key})${opts.signing ? ` · ${opts.signing}` : ""}`;
}

/** Recent commit messages, newest first, without duplicates. */
export class MessageHistory {
  static readonly LIMIT = 30;
  private items: string[];

  constructor(items: readonly string[] = []) {
    this.items = items.filter((m) => m.trim()).slice(0, MessageHistory.LIMIT);
  }

  add(message: string): void {
    const m = message.trim();
    if (!m) {
      return;
    }
    this.items = [m, ...this.items.filter((x) => x !== m)].slice(0, MessageHistory.LIMIT);
  }

  get entries(): readonly string[] {
    return this.items;
  }
}

/**
 * Line numbers (1-based) that open or close a conflict: Oxygen's markers
 * (`<<<<<<< oxy conflict …`) and Git's alike, since both begin with seven
 * angle brackets.
 */
export function conflictMarkerLines(text: string): number[] {
  const out: number[] = [];
  text.split("\n").forEach((l, i) => {
    if (/^(<{7}|>{7})( |\r?$)/.test(l)) {
      out.push(i + 1);
    }
  });
  return out;
}