# file_cache.py
"""
Persistent cache of Anthropic Files API uploads.

Maps (absolute_path, mtime_ns, size_bytes) -> file_id so we only upload each
file once and reuse the file_id on subsequent sends.  If the file has changed
on disk the old file_id is deleted from the API and a new one is uploaded.

Cache is stored as JSON at ./logs/file_cache.json so it survives restarts.
"""

import json
import os
import datetime
from pathlib import Path
from typing import Optional

_CACHE_PATH = Path("./logs/file_cache.json")

# in-memory dict:  abs_path_str -> {"file_id": str, "mtime_ns": int, "size": int}
_cache: dict[str, dict] = {}
_cache_loaded = False

_anthropic_client = None  # set by _ensure_client()


# ------------------------------------------------------------------ persistence

def _load_cache():
    global _cache, _cache_loaded
    if _cache_loaded:
        return
    _cache_loaded = True
    if _CACHE_PATH.exists():
        try:
            _cache = json.loads(_CACHE_PATH.read_text(encoding="utf-8"))
        except Exception:
            _cache = {}
    else:
        _cache = {}


def _save_cache():
    _CACHE_PATH.parent.mkdir(parents=True, exist_ok=True)
    _CACHE_PATH.write_text(json.dumps(_cache, indent=2, ensure_ascii=False), encoding="utf-8")


# ------------------------------------------------------------------ anthropic client

def _ensure_client():
    global _anthropic_client
    if _anthropic_client is not None:
        return _anthropic_client
    import tomllib
    import anthropic
    with open("credentials.toml", "rb") as f:
        creds = tomllib.load(f)
    _anthropic_client = anthropic.Anthropic(api_key=creds["anthropic"]["api_key"])
    return _anthropic_client


def reset_client():
    """Called when the main ai_client resets its session."""
    global _anthropic_client
    _anthropic_client = None


# ------------------------------------------------------------------ MIME helpers

_MIME_BY_EXT = {
    ".pdf":  "application/pdf",
    ".txt":  "text/plain",
    ".md":   "text/plain",
    ".py":   "text/plain",
    ".toml": "text/plain",
    ".json": "text/plain",
    ".yaml": "text/plain",
    ".yml":  "text/plain",
    ".ini":  "text/plain",
    ".ps1":  "text/plain",
    ".csv":  "text/plain",
    ".log":  "text/plain",
    ".png":  "image/png",
    ".jpg":  "image/jpeg",
    ".jpeg": "image/jpeg",
    ".gif":  "image/gif",
    ".webp": "image/webp",
}

# File types that can be sent as 'document' blocks
_DOCUMENT_MIMES = {"application/pdf", "text/plain"}
# File types that can be sent as 'image' blocks
_IMAGE_MIMES = {"image/png", "image/jpeg", "image/gif", "image/webp"}


def _mime_for(path: Path) -> str:
    return _MIME_BY_EXT.get(path.suffix.lower(), "text/plain")


def content_block_type(path: Path) -> str:
    """Returns 'document', 'image', or 'unsupported'."""
    mime = _mime_for(path)
    if mime in _DOCUMENT_MIMES:
        return "document"
    if mime in _IMAGE_MIMES:
        return "image"
    return "unsupported"


# ------------------------------------------------------------------ upload / cache logic

def _stat(path: Path) -> tuple[int, int]:
    """Returns (mtime_ns, size_bytes). Raises if file missing."""
    st = path.stat()
    return int(st.st_mtime_ns), int(st.st_size)


def _delete_remote(file_id: str):
    """Best-effort delete of a stale file_id from the API."""
    try:
        client = _ensure_client()
        client.beta.files.delete(file_id, extra_headers={"anthropic-beta": "files-api-2025-04-14"})
    except Exception:
        pass  # stale deletes are non-fatal


def _upload(path: Path) -> str:
    """Upload the file and return its new file_id."""
    client = _ensure_client()
    mime = _mime_for(path)
    filename = path.name
    with open(path, "rb") as fh:
        result = client.beta.files.upload(
            file=(filename, fh, mime),
            extra_headers={"anthropic-beta": "files-api-2025-04-14"},
        )
    return result.id


def get_file_id(path: Path) -> Optional[str]:
    """
    Return a valid Anthropic file_id for the given path, uploading if needed.
    Returns None if the file type is unsupported.
    Raises on network / API errors.
    """
    _load_cache()

    if content_block_type(path) == "unsupported":
        return None

    abs_str = str(path.resolve())
    try:
        mtime_ns, size = _stat(path)
    except FileNotFoundError:
        # File gone - evict from cache
        if abs_str in _cache:
            _delete_remote(_cache[abs_str]["file_id"])
            del _cache[abs_str]
            _save_cache()
        return None

    entry = _cache.get(abs_str)
    if entry and entry.get("mtime_ns") == mtime_ns and entry.get("size") == size:
        # Cache hit - file unchanged
        return entry["file_id"]

    # Cache miss or stale - delete old remote if we had one
    if entry:
        _delete_remote(entry["file_id"])

    file_id = _upload(path)
    _cache[abs_str] = {"file_id": file_id, "mtime_ns": mtime_ns, "size": size}
    _save_cache()
    return file_id


def evict(path: Path):
    """Manually evict a path from the cache (e.g. after a tool-call write)."""
    _load_cache()
    abs_str = str(path.resolve())
    entry = _cache.pop(abs_str, None)
    if entry:
        _delete_remote(entry["file_id"])
        _save_cache()


def list_cached() -> list[dict]:
    """Return a snapshot of the current cache for display."""
    _load_cache()
    return [
        {"path": k, **v}
        for k, v in _cache.items()
    ]