from __future__ import annotations

from pathlib import Path

from .status import project_stage, task_counts
from .tasks import get_next_task


def build_handoff(root: Path) -> str:
    next_task = get_next_task(root)
    counts = task_counts(root)
    lines = [
        "# AI Agent Handoff",
        "",
        f"Project stage: {project_stage(root)}",
        "",
        "## Task Counts",
    ]
    if counts:
        for status, count in counts.items():
            lines.append(f"- {status}: {count}")
    else:
        lines.append("- No tasks found")

    lines.extend(["", "## Next Task"])
    if next_task:
        lines.extend([
            f"- ID: {next_task.task_id}",
            f"- Title: {next_task.title}",
            f"- Status: {next_task.status}",
        ])
    else:
        lines.append("No Todo task found.")

    lines.extend([
        "",
        "## Agent Rules",
        "- Implement one task only.",
        "- Make the smallest useful change possible.",
        "- Do not rewrite unrelated code.",
        "- Run relevant tests.",
        "- Update documentation if behaviour changes.",
        "- Report files changed, validation, risks, and next recommended task.",
    ])
    return "\n".join(lines) + "\n"