import type { ExtensionAPI, ExtensionContext, SessionEntry } from "@earendil-works/pi-coding-agent";
import type { TreeLabelerSettings } from "./types.ts";

function normalize(value: string, maxChars: number): string | undefined {
  const cleaned = value
    .replace(/\u001b\[[0-?]*[ -\/]*[@-~]/g, "")
    .replace(/[\u0000-\u001f\u007f]+/g, " ")
    .replace(/\s+/g, " ")
    .trim()
    .replace(/^[`'\"]+|[`'\"]+$/g, "")
    .trim();
  if (!cleaned) return undefined;
  return cleaned.length <= maxChars ? cleaned : `${cleaned.slice(0, Math.max(1, maxChars - 1)).trimEnd()}…`;
}

function messageText(entry: SessionEntry): string | undefined {
  if (entry.type !== "message" || entry.message.role !== "user") return undefined;
  const content = entry.message.content;
  if (typeof content === "string") return content;
  if (!Array.isArray(content)) return undefined;
  return content
    .filter((block): block is { type: "text"; text: string } => block.type === "text")
    .map((block) => block.text)
    .join(" ");
}

export function deriveCheckedOutSectionName(
  branch: SessionEntry[],
  getLabel: (entryId: string) => string | undefined,
  settings: TreeLabelerSettings["sessionNaming"],
): string | undefined {
  if (!settings.enabled) return undefined;
  for (let index = branch.length - 1; index >= 0; index--) {
    const label = getLabel(branch[index].id);
    if (label) return normalize(label, settings.maxChars);
  }
  if (!settings.fallbackToMessage) return undefined;
  for (let index = branch.length - 1; index >= 0; index--) {
    const text = messageText(branch[index]);
    if (text) return normalize(text, settings.maxChars);
  }
  return undefined;
}

export function syncSessionName(pi: ExtensionAPI, ctx: ExtensionContext, settings: TreeLabelerSettings): string | undefined {
  const name = deriveCheckedOutSectionName(
    ctx.sessionManager.getBranch(),
    (entryId) => ctx.sessionManager.getLabel(entryId),
    settings.sessionNaming,
  );
  if (name && name !== ctx.sessionManager.getSessionName()) pi.setSessionName(name);
  return name;
}