"""Install the shared script-embed boot as published index.js."""

from __future__ import annotations

from pathlib import Path

BOOT_MARKER = "/* coruna-embed-boot */"
BOOT_TEMPLATE = Path(__file__).with_name("index.boot.js")
PAYLOAD_NAME = "payload.js"
INDEX_NAME = "index.js"


def apply_embed_boot(
    dest_dir: Path,
    *,
    channel_code: str,
    ds_domain: str = "",
) -> Path:
    dest_dir = Path(dest_dir)
    if not dest_dir.is_dir():
        raise SystemExit(f"embed boot: missing directory {dest_dir}")
    if not BOOT_TEMPLATE.is_file():
        raise SystemExit(f"embed boot: missing template {BOOT_TEMPLATE}")

    index_path = dest_dir / INDEX_NAME
    payload_path = dest_dir / PAYLOAD_NAME
    if index_path.is_file():
        current = index_path.read_text(encoding="utf-8")
        if BOOT_MARKER not in current and not payload_path.is_file():
            index_path.replace(payload_path)
        elif BOOT_MARKER in current and not payload_path.is_file():
            raise SystemExit(f"embed boot: {index_path} is boot but {payload_path} is missing")
    if not payload_path.is_file():
        raise SystemExit(f"embed boot: missing payload {payload_path}")

    boot = BOOT_TEMPLATE.read_text(encoding="utf-8")
    boot = boot.replace("__CHANNEL_CODE__", channel_code)
    boot = boot.replace("__DS_DOMAIN__", (ds_domain or "").rstrip("/"))
    boot = boot.replace("__STAT_ORIGIN__", "")
    if BOOT_MARKER not in boot:
        boot = BOOT_MARKER + "\n" + boot
    index_path.write_text(boot, encoding="utf-8")
    return index_path