import json
import random
from pathlib import Path
from datetime import datetime
from config import settings


_ADJECTIVES = [
    "amber", "azure", "bold", "bright", "calm", "cedar", "cobalt", "coral",
    "crisp", "dusk", "ember", "fern", "frost", "gold", "hazy", "indigo",
    "jade", "keen", "lark", "lunar", "maple", "misty", "noble", "north",
    "oak", "onyx", "opal", "pine", "quiet", "raven", "ridge", "river",
    "sage", "silver", "slate", "solar", "steel", "stone", "swift", "teal",
    "timber", "vale", "velvet", "violet", "warm", "wild", "winter", "wren",
]

_NOUNS = [
    "bay", "bloom", "brook", "canyon", "cave", "cliff", "cloud", "coast",
    "creek", "dale", "dawn", "delta", "dune", "echo", "falls", "field",
    "fjord", "flare", "glade", "glen", "grove", "harbor", "haven", "hill",
    "hollow", "isle", "lake", "ledge", "marsh", "meadow", "mist", "moon",
    "moor", "peak", "plain", "pond", "reef", "ridge", "rise", "rock",
    "shore", "sky", "slope", "spring", "star", "storm", "trail", "vale",
    "wave", "wood",
]


def generate_session_id() -> str:
    """Return a readable slug like 'amber-lake' or 'amber-lake-03'."""
    existing = {s["session_id"] for s in list_all()}
    for _ in range(30):
        base = f"{random.choice(_ADJECTIVES)}-{random.choice(_NOUNS)}"
        if base not in existing:
            return base
        # Try with a numeric suffix
        candidate = f"{base}-{random.randint(2, 99):02d}"
        if candidate not in existing:
            return candidate
    # Statistically unreachable for a personal tool
    import uuid
    return str(uuid.uuid4())[:8]


def _path(session_id: str) -> Path:
    d = settings.sessions_path()
    d.mkdir(parents=True, exist_ok=True)
    return d / f"{session_id}.json"


def load(session_id: str) -> list[dict]:
    path = _path(session_id)
    if not path.exists():
        return []
    return json.loads(path.read_text()).get("messages", [])


def save(session_id: str, messages: list[dict]) -> None:
    path = _path(session_id)
    existing = json.loads(path.read_text()) if path.exists() else {}

    # Enforce rolling window
    windowed = messages[-settings.max_history_messages:]

    path.write_text(json.dumps({
        "session_id": session_id,
        "created": existing.get("created", datetime.now().isoformat()),
        "updated": datetime.now().isoformat(),
        "messages": windowed,
    }, indent=2))


def list_all() -> list[dict]:
    d = settings.sessions_path()
    if not d.exists():
        return []
    results = []
    for f in sorted(d.glob("*.json"), key=lambda p: p.stat().st_mtime, reverse=True):
        try:
            data = json.loads(f.read_text())
            results.append({
                "session_id": data["session_id"],
                "updated": data.get("updated"),
                "message_count": len(data.get("messages", [])),
            })
        except Exception:
            pass
    return results