"""Bundle export — the only channel to noteman (ADR 0001).

    song.zip
      song.json
      original.pdf
      001.webp 002.webp …

Array order in `song.json` *is* slice order: one ordering, not two. Markers
nest inside the slice they sit on, so an index appears in exactly one place —
a jump source's `destination`.
"""

from __future__ import annotations

import json
import zipfile
from pathlib import Path

from .pdf import Source
from .project import Project
from .render import render_song

FORMAT_VERSION = 1
METADATA_FIELDS = (
    "title",
    "subtitle",
    "composer",
    "original_artist",
    "arranger",
    "lyricist",
    "translator",
    "voices",
)


def song_json(project: Project, files: list[str]) -> dict:
    payload: dict = {"v": FORMAT_VERSION}
    for field in METADATA_FIELDS:
        value = project.metadata.get(field)
        if value:
            payload[field] = value
    payload["slices"] = [{"file": name} for name in files]
    return payload


def write(project: Project, source: Source, path: Path) -> Path:
    """Render the song and write the bundle. Returns the zip path."""
    images = render_song(project, source)
    names = [f"{i + 1:03}.webp" for i in range(len(images))]

    path = Path(path)
    path.parent.mkdir(parents=True, exist_ok=True)
    # ZIP_STORED for the images: WebP is already compressed, so deflating it
    # only costs time. The JSON is small enough not to care.
    with zipfile.ZipFile(path, "w") as zf:
        zf.writestr(
            "song.json",
            json.dumps(song_json(project, names), indent=2, ensure_ascii=False),
            zipfile.ZIP_DEFLATED,
        )
        if project.source.exists():
            zf.write(project.source, "original.pdf")
        for name, data in zip(names, images):
            zf.writestr(name, data, zipfile.ZIP_STORED)

    # The project is spent once its song has been exported: the next edit
    # session starts fresh from detection rather than resuming these decisions.
    # Recorded here so no caller can forget it.
    project.exported = True
    project.save()
    return path