#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
Codex Session Start Hook - Inject Trellis context into Codex sessions.

Output format follows Codex hook protocol:
  stdout JSON → { hookSpecificOutput: { hookEventName: "SessionStart", additionalContext: "..." } }
"""

from __future__ import annotations

import json
import os
import subprocess
import sys
import warnings
from io import StringIO
from pathlib import Path

warnings.filterwarnings("ignore")


def should_skip_injection() -> bool:
    return os.environ.get("CODEX_NON_INTERACTIVE") == "1"


def read_file(path: Path, fallback: str = "") -> str:
    try:
        return path.read_text(encoding="utf-8")
    except (FileNotFoundError, PermissionError):
        return fallback


def run_script(script_path: Path) -> str:
    try:
        env = os.environ.copy()
        env["PYTHONIOENCODING"] = "utf-8"
        cmd = [sys.executable, "-W", "ignore", str(script_path)]
        result = subprocess.run(
            cmd,
            capture_output=True,
            text=True,
            encoding="utf-8",
            errors="replace",
            timeout=5,
            cwd=str(script_path.parent.parent.parent),
            env=env,
        )
        return result.stdout if result.returncode == 0 else "No context available"
    except (subprocess.TimeoutExpired, FileNotFoundError, PermissionError):
        return "No context available"


def _normalize_task_ref(task_ref: str) -> str:
    normalized = task_ref.strip()
    if not normalized:
        return ""

    path_obj = Path(normalized)
    if path_obj.is_absolute():
        return str(path_obj)

    normalized = normalized.replace("\\", "/")
    while normalized.startswith("./"):
        normalized = normalized[2:]

    if normalized.startswith("tasks/"):
        return f".trellis/{normalized}"

    return normalized


def _resolve_task_dir(trellis_dir: Path, task_ref: str) -> Path:
    normalized = _normalize_task_ref(task_ref)
    path_obj = Path(normalized)
    if path_obj.is_absolute():
        return path_obj
    if normalized.startswith(".trellis/"):
        return trellis_dir.parent / path_obj
    return trellis_dir / "tasks" / path_obj


def _get_task_status(trellis_dir: Path) -> str:
    current_task_file = trellis_dir / ".current-task"
    if not current_task_file.is_file():
        return "Status: NO ACTIVE TASK\nNext: Describe what you want to work on"

    task_ref = _normalize_task_ref(current_task_file.read_text(encoding="utf-8").strip())
    if not task_ref:
        return "Status: NO ACTIVE TASK\nNext: Describe what you want to work on"

    task_dir = _resolve_task_dir(trellis_dir, task_ref)
    if not task_dir.is_dir():
        return f"Status: STALE POINTER\nTask: {task_ref}\nNext: Task directory not found. Run: python3 ./.trellis/scripts/task.py finish"

    task_json_path = task_dir / "task.json"
    task_data: dict = {}
    if task_json_path.is_file():
        try:
            task_data = json.loads(task_json_path.read_text(encoding="utf-8"))
        except (json.JSONDecodeError, PermissionError):
            pass

    task_title = task_data.get("title", task_ref)
    task_status = task_data.get("status", "unknown")

    if task_status == "completed":
        return f"Status: COMPLETED\nTask: {task_title}\nNext: Archive with `python3 ./.trellis/scripts/task.py archive {task_dir.name}` or start a new task"

    has_context = False
    for jsonl_name in ("implement.jsonl", "check.jsonl", "spec.jsonl"):
        jsonl_path = task_dir / jsonl_name
        if jsonl_path.is_file() and jsonl_path.stat().st_size > 0:
            has_context = True
            break

    has_prd = (task_dir / "prd.md").is_file()

    if not has_prd:
        return f"Status: NOT READY\nTask: {task_title}\nMissing: prd.md not created\nNext: Write PRD, then research → init-context → start"

    if not has_context:
        return f"Status: NOT READY\nTask: {task_title}\nMissing: Context not configured (no jsonl files)\nNext: Complete Phase 2 (research → init-context → start) before implementing"

    return f"Status: READY\nTask: {task_title}\nNext: Continue with implement or check"


def _build_workflow_toc(workflow_path: Path) -> str:
    """Build a compact section index for workflow.md (lazy-load the full file on demand).

    Replaces full-file injection to keep additionalContext payload small.
    The full file is accessible via: Read tool on .trellis/workflow.md
    """
    content = read_file(workflow_path)
    if not content:
        return "No workflow.md found"

    toc_lines = [
        "# Development Workflow — Section Index",
        "Full guide: .trellis/workflow.md  (read on demand)",
        "",
    ]
    for line in content.splitlines():
        if line.startswith("## "):
            toc_lines.append(line)

    toc_lines += [
        "",
        "To read a section: use the Read tool on .trellis/workflow.md",
    ]
    return "\n".join(toc_lines)


def main() -> None:
    if should_skip_injection():
        sys.exit(0)

    # Read hook input from stdin
    try:
        hook_input = json.loads(sys.stdin.read())
        project_dir = Path(hook_input.get("cwd", ".")).resolve()
    except (json.JSONDecodeError, KeyError):
        project_dir = Path(".").resolve()

    trellis_dir = project_dir / ".trellis"

    output = StringIO()

    output.write("""<session-context>
You are starting a new session in a Trellis-managed project.
Read and follow all instructions below carefully.
</session-context>

""")

    output.write("<current-state>\n")
    context_script = trellis_dir / "scripts" / "get_context.py"
    output.write(run_script(context_script))
    output.write("\n</current-state>\n\n")

    output.write("<workflow>\n")
    output.write(_build_workflow_toc(trellis_dir / "workflow.md"))
    output.write("\n</workflow>\n\n")

    output.write("<guidelines>\n")
    output.write("**Note**: The guidelines below are index files — they list available guideline documents and their locations.\n")
    output.write("During actual development, you MUST read the specific guideline files listed in each index's Pre-Development Checklist.\n\n")

    spec_dir = trellis_dir / "spec"
    if spec_dir.is_dir():
        for sub in sorted(spec_dir.iterdir()):
            if not sub.is_dir() or sub.name.startswith("."):
                continue

            if sub.name == "guides":
                index_file = sub / "index.md"
                if index_file.is_file():
                    output.write(f"## {sub.name}\n")
                    output.write(read_file(index_file))
                    output.write("\n\n")
                continue

            index_file = sub / "index.md"
            if index_file.is_file():
                output.write(f"## {sub.name}\n")
                output.write(read_file(index_file))
                output.write("\n\n")
            else:
                for nested in sorted(sub.iterdir()):
                    if not nested.is_dir():
                        continue
                    nested_index = nested / "index.md"
                    if nested_index.is_file():
                        output.write(f"## {sub.name}/{nested.name}\n")
                        output.write(read_file(nested_index))
                        output.write("\n\n")

    output.write("</guidelines>\n\n")

    task_status = _get_task_status(trellis_dir)
    output.write(f"<task-status>\n{task_status}\n</task-status>\n\n")

    output.write("""<ready>
Context loaded. Workflow index, project state, and guidelines are already injected above — do NOT re-read them.
Wait for the user's first message, then handle it following the workflow guide.
If there is an active task, ask whether to continue it.
</ready>""")

    context = output.getvalue()
    result = {
        "suppressOutput": True,
        "systemMessage": f"Trellis context injected ({len(context)} chars)",
        "hookSpecificOutput": {
            "hookEventName": "SessionStart",
            "additionalContext": context,
        },
    }

    print(json.dumps(result, ensure_ascii=False), flush=True)


if __name__ == "__main__":
    main()