#!/usr/bin/env python3
"""
Context Guardian — Snapshot Manager.

Cria, lista e le snapshots de contexto para preservacao
pre-compactacao. Os snapshots sao arquivos .md estruturados
com todas as informacoes criticas de uma sessao.

Uso:
    python context_snapshot.py save --project "nome" --phase "fase" --summary "resumo"
    python context_snapshot.py list
    python context_snapshot.py latest
    python context_snapshot.py read <snapshot-file>
    python context_snapshot.py prune --keep 10
"""

import json
import sys
import os
import re
import stat
from datetime import datetime
from pathlib import Path

# ── Paths ──────────────────────────────────────────────────────────────────
SCRIPT_DIR = Path(__file__).resolve().parent
SKILL_DIR = SCRIPT_DIR.parent
DATA_DIR = SKILL_DIR / "data"
SNAPSHOT_NAME = re.compile(r"\Asnapshot-\d{8}-\d{6}\.md\Z")

# ── Functions ──────────────────────────────────────────────────────────────

def ensure_data_dir():
    """Create data directory if it doesn't exist."""
    DATA_DIR.mkdir(parents=True, exist_ok=True)


def snapshot_path(filename: str, *, must_exist: bool = True) -> Path:
    """Resolve a canonical snapshot name without following links."""
    if not isinstance(filename, str) or not SNAPSHOT_NAME.fullmatch(filename):
        raise ValueError("Nome de snapshot invalido")
    filepath = DATA_DIR / filename
    if must_exist:
        try:
            stat = filepath.lstat()
        except FileNotFoundError:
            raise FileNotFoundError(filename) from None
        if filepath.is_symlink() or not filepath.is_file():
            raise ValueError("Snapshot deve ser um arquivo regular")
    return filepath


def read_snapshot_file(filepath: Path) -> str:
    flags = os.O_RDONLY | getattr(os, "O_NOFOLLOW", 0)
    descriptor = os.open(filepath, flags)
    try:
        if not stat.S_ISREG(os.fstat(descriptor).st_mode):
            raise ValueError("Snapshot deve ser um arquivo regular")
        with os.fdopen(descriptor, "r", encoding="utf-8") as handle:
            descriptor = -1
            return handle.read()
    finally:
        if descriptor >= 0:
            os.close(descriptor)


def save_snapshot(project: str = "", phase: str = "", summary: str = "") -> str:
    """
    Create a new snapshot file with metadata header.
    Returns the path to the created file.

    The Claude agent is expected to APPEND the actual content
    (extracted from the conversation) after this header is created.
    """
    ensure_data_dir()

    timestamp = datetime.now().strftime("%Y%m%d-%H%M%S")
    filename = f"snapshot-{timestamp}.md"
    filepath = snapshot_path(filename, must_exist=False)

    header = f"""# Context Guardian Snapshot — {datetime.now().strftime('%Y-%m-%d %H:%M:%S')}
**Projeto**: {project or 'nao especificado'}
**Fase**: {phase or 'nao especificada'}
**Resumo**: {summary or 'snapshot pre-compactacao'}
**Modelo**: claude-opus-4-6

---

<!-- O Claude deve preencher as secoes abaixo seguindo references/extraction-protocol.md -->

## Arquivos Tocados
| Arquivo | Acao | Detalhes |
|---------|------|----------|
| | | |

## Decisoes
- (preencher)

## Correcoes
- (preencher)

## Progresso
- Total de tarefas:
- Concluidas:
- Pendentes:

## Trechos Criticos
- (preencher)

## Padroes Observados
- (preencher)

## Dependencias
- (preencher)

## Contexto do Usuario
- Objetivo:
- Proxima acao esperada:

---
*Snapshot gerado por context-guardian v1.0.0*
*Para restaurar: leia este arquivo + MEMORY.md + context_manager.py load*
"""

    filepath.write_text(header, encoding="utf-8")
    return str(filepath)


def list_snapshots() -> list[dict]:
    """List all snapshots with metadata."""
    ensure_data_dir()
    snapshots = []

    for f in sorted(DATA_DIR.iterdir(), reverse=True):
        if not SNAPSHOT_NAME.fullmatch(f.name) or f.is_symlink() or not f.is_file():
            continue
        stat = f.lstat()
        snapshots.append({
            "file": f.name,
            "path": str(f),
            "size_kb": round(stat.st_size / 1024, 1),
            "modified": datetime.fromtimestamp(stat.st_mtime).strftime("%Y-%m-%d %H:%M:%S"),
        })

    return snapshots


def read_latest() -> dict:
    """Read the most recent snapshot."""
    snapshots = list_snapshots()
    if not snapshots:
        return {"error": "Nenhum snapshot encontrado."}

    latest = snapshots[0]
    path = snapshot_path(latest["file"])
    content = read_snapshot_file(path)

    return {
        "file": latest["file"],
        "path": latest["path"],
        "size_kb": latest["size_kb"],
        "content": content,
    }


def read_snapshot(filename: str) -> dict:
    """Read a specific snapshot by filename."""
    try:
        filepath = snapshot_path(filename)
    except (ValueError, FileNotFoundError) as error:
        return {"error": f"Arquivo invalido ou nao encontrado: {filename}", "detail": str(error)}

    content = read_snapshot_file(filepath)
    return {
        "file": filename,
        "path": str(filepath),
        "content": content,
    }


def prune_snapshots(keep: int = 10) -> dict:
    """Remove old snapshots, keeping the N most recent."""
    snapshots = list_snapshots()
    if len(snapshots) <= keep:
        return {"pruned": 0, "remaining": len(snapshots)}

    to_remove = snapshots[keep:]
    for s in to_remove:
        snapshot_path(s["file"]).unlink()

    return {"pruned": len(to_remove), "remaining": keep}


# ── CLI ────────────────────────────────────────────────────────────────────

def main():
    args = sys.argv[1:]

    if not args:
        print(json.dumps({
            "error": "Comando necessario: save, list, latest, read, prune",
            "usage": "python context_snapshot.py <command> [options]",
        }, indent=2, ensure_ascii=False))
        sys.exit(1)

    cmd = args[0]

    if cmd == "save":
        project = ""
        phase = ""
        summary = ""
        i = 1
        while i < len(args):
            if args[i] == "--project" and i + 1 < len(args):
                project = args[i + 1]
                i += 2
            elif args[i] == "--phase" and i + 1 < len(args):
                phase = args[i + 1]
                i += 2
            elif args[i] == "--summary" and i + 1 < len(args):
                summary = args[i + 1]
                i += 2
            else:
                i += 1

        path = save_snapshot(project, phase, summary)
        print(json.dumps({
            "status": "ok",
            "action": "snapshot_created",
            "path": path,
            "next_step": "Preencher o snapshot com dados extraidos da conversa",
        }, indent=2, ensure_ascii=False))

    elif cmd == "list":
        snapshots = list_snapshots()
        print(json.dumps({
            "total": len(snapshots),
            "snapshots": snapshots,
        }, indent=2, ensure_ascii=False))

    elif cmd == "latest":
        result = read_latest()
        print(json.dumps(result, indent=2, ensure_ascii=False))

    elif cmd == "read" and len(args) > 1:
        result = read_snapshot(args[1])
        print(json.dumps(result, indent=2, ensure_ascii=False))

    elif cmd == "prune":
        keep = 10
        if "--keep" in args:
            idx = args.index("--keep")
            if idx + 1 < len(args):
                keep = int(args[idx + 1])
        result = prune_snapshots(keep)
        print(json.dumps(result, indent=2, ensure_ascii=False))

    else:
        print(json.dumps({"error": f"Comando desconhecido: {cmd}"}, indent=2))
        sys.exit(1)


if __name__ == "__main__":
    main()