"""Write or append daily summaries to Obsidian notes."""

from datetime import datetime, timezone
from pathlib import Path
from typing import List

from .git_tracker import RepoSummary
from .zed_tracker import ProjectSummary

DAILY_NOTE_FORMAT = "%Y-%m-%d"
SECTION_HEADER = "## Coding Work"


def _format_time(ts: int) -> str:
    """Format a Unix timestamp as HH:MM."""
    dt = datetime.fromtimestamp(ts, tz=timezone.utc).astimezone()
    return dt.strftime("%H:%M")


def generate_markdown(
    zed_projects: List[ProjectSummary],
    git_repos: List[RepoSummary],
    date: datetime,
) -> str:
    """Generate the markdown content for the daily summary."""
    lines = []
    lines.append(SECTION_HEADER)
    lines.append("")

    if not zed_projects and not git_repos:
        lines.append("No coding activity tracked today. 🌴")
        return "\n".join(lines)

    if zed_projects:
        lines.append("### Zed Editors")
        lines.append("")
        for project in zed_projects:
            langs = (
                f" ({', '.join(sorted(project.languages))})"
                if project.languages
                else ""
            )
            lines.append(
                f"- **{project.project}**{langs} — {len(project.files)} file(s)"
            )
            # Show up to 5 most recent files
            for path, mtime in project.files[:5]:
                time_str = _format_time(mtime)
                lines.append(f"  - `{Path(path).name}` at {time_str}")
            if len(project.files) > 5:
                lines.append(f"  - *…and {len(project.files) - 5} more*")
        lines.append("")

    if git_repos:
        lines.append("### Git Commits")
        lines.append("")
        for repo in git_repos:
            lines.append(
                f"- **{repo.name}** — {len(repo.commits)} commit(s), "
                f"+{repo.total_insertions}/-{repo.total_deletions} lines, "
                f"{repo.total_files} file(s)"
            )
            for commit in repo.commits:
                time_str = _format_time(commit.timestamp)
                lines.append(f"  - `{commit.hash}` {commit.message} — {time_str}")
        lines.append("")

    return "\n".join(lines)


# Backward compatibility alias
_generate_markdown = generate_markdown


def write_daily_summary(
    vault_path: Path,
    zed_projects: List[ProjectSummary],
    git_repos: List[RepoSummary],
    daily_folder: str = "Daily Notes",
    date: datetime = None,
) -> Path:
    """Write or append a coding summary to the Obsidian daily note."""
    if date is None:
        date = datetime.now(timezone.utc).astimezone()

    note_dir = vault_path / daily_folder
    note_dir.mkdir(parents=True, exist_ok=True)

    note_name = date.strftime(DAILY_NOTE_FORMAT)
    note_path = note_dir / f"{note_name}.md"

    content = _generate_markdown(zed_projects, git_repos, date)

    if note_path.exists():
        existing = note_path.read_text(encoding="utf-8")
        # If section already exists, replace it; otherwise append
        if SECTION_HEADER in existing:
            before, _, after = existing.partition(SECTION_HEADER)
            # Find the next section header or end of file
            next_section_idx = after.find("\n## ")
            if next_section_idx != -1:
                after = after[next_section_idx:]
            else:
                after = ""
            new_content = before.rstrip() + "\n\n" + content + "\n" + after.lstrip()
        else:
            new_content = existing.rstrip() + "\n\n" + content + "\n"
    else:
        new_content = f"# {note_name}\n\n" + content + "\n"

    note_path.write_text(new_content, encoding="utf-8")
    return note_path