#!/usr/bin/env python3
"""Provide FESA handoff context at Codex session startup/resume."""

from __future__ import annotations

import json
import sys
from pathlib import Path


MAX_SECTION_CHARS = 700


def find_repo_root(start: Path) -> Path:
    for candidate in (start, *start.parents):
        if (candidate / "AGENTS.md").exists() and (candidate / "PLAN.md").exists():
            return candidate
    return start


def read_text(path: Path) -> str:
    try:
        return path.read_text(encoding="utf-8")
    except OSError:
        return ""


def section(markdown: str, heading: str) -> str:
    marker = f"## {heading}"
    start = markdown.find(marker)
    if start < 0:
        return ""
    start = markdown.find("\n", start)
    if start < 0:
        return ""
    end = markdown.find("\n## ", start + 1)
    body = markdown[start:end if end >= 0 else len(markdown)].strip()
    body = " ".join(line.strip() for line in body.splitlines() if line.strip())
    if len(body) > MAX_SECTION_CHARS:
        body = body[:MAX_SECTION_CHARS].rstrip() + "..."
    return body


def main() -> int:
    try:
        payload = json.load(sys.stdin)
    except json.JSONDecodeError:
        payload = {}

    root = find_repo_root(Path(payload.get("cwd") or ".").resolve())
    plan = read_text(root / "PLAN.md")
    progress = read_text(root / "PROGRESS.md")

    context_lines = [
        "FESA session startup context:",
        "- Before planning or editing, read AGENTS.md, PROGRESS.md, PLAN.md, and docs/README.md.",
        "- Keep completed work in PROGRESS.md and future tasks/open decisions in PLAN.md.",
    ]

    current_objective = section(plan, "Current Objective")
    if current_objective:
        context_lines.append(f"- Current objective: {current_objective}")

    current_status = section(progress, "Current Status")
    if current_status:
        context_lines.append(f"- Current status: {current_status}")

    blockers = section(progress, "Known Blockers") or section(plan, "Open Questions")
    if blockers:
        context_lines.append(f"- Blockers/open questions: {blockers}")

    json.dump(
        {
            "hookSpecificOutput": {
                "hookEventName": "SessionStart",
                "additionalContext": "\n".join(context_lines),
            }
        },
        sys.stdout,
    )
    return 0


if __name__ == "__main__":
    raise SystemExit(main())