"""Configuration loader — reads ~/.obsidian-rag/config.json (or ./obsidian-rag/ for dev)."""

from __future__ import annotations

import json
import os
from enum import Enum
from dataclasses import dataclass, field
from pathlib import Path
from typing import Any


DEFAULT_CONFIG_DIR = Path(__file__).parent.parent.parent  # python/ → project root


@dataclass
class EmbeddingConfig:
    provider: str = "ollama"
    model: str = "mxbai-embed-large"
    base_url: str = "http://localhost:11434"
    dimensions: int = 1024
    batch_size: int = 64


@dataclass
class VectorStoreConfig:
    type: str = "lancedb"
    path: str = ""  # resolved relative to data_dir


@dataclass
class IndexingConfig:
    chunk_size: int = 500
    chunk_overlap: int = 100
    file_patterns: list[str] = field(default_factory=lambda: ["*.md"])
    deny_dirs: list[str] = field(
        default_factory=lambda: [".obsidian", ".trash", "zzz-Archive", ".git", ".logseq"]
    )
    allow_dirs: list[str] = field(default_factory=list)


@dataclass
class SecurityConfig:
    require_confirmation_for: list[str] = field(default_factory=lambda: ["health", "financial_debt"])
    sensitive_sections: list[str] = field(
        default_factory=lambda: ["#mentalhealth", "#physicalhealth", "#Relations"]
    )
    local_only: bool = True


@dataclass
class MemoryConfig:
    auto_suggest: bool = True
    patterns: dict[str, list[str]] = field(
        default_factory=lambda: {
            "financial": ["owe", "owed", "debt", "paid", "$", "spent", "spend"],
            "health": ["#mentalhealth", "#physicalhealth", "medication", "therapy"],
            "commitments": ["shopping list", "costco", "amazon", "grocery"],
        }
    )


@dataclass
class ObsidianRagConfig:
    vault_path: str = ""
    embedding: EmbeddingConfig = field(default_factory=EmbeddingConfig)
    vector_store: VectorStoreConfig = field(default_factory=VectorStoreConfig)
    indexing: IndexingConfig = field(default_factory=IndexingConfig)
    security: SecurityConfig = field(default_factory=SecurityConfig)
    memory: MemoryConfig = field(default_factory=MemoryConfig)


def _resolve_data_dir() -> Path:
    """Resolve the data directory: dev (project root/obsidian-rag/) or production (~/.obsidian-rag/)."""
    dev_data_dir = DEFAULT_CONFIG_DIR / "obsidian-rag"
    if dev_data_dir.exists() or (DEFAULT_CONFIG_DIR / "KnowledgeVault").exists():
        return dev_data_dir
    # Production: ~/.obsidian-rag/
    return Path(os.path.expanduser("~/.obsidian-rag"))


def load_config(config_path: str | Path | None = None) -> ObsidianRagConfig:
    """Load config from JSON file, falling back to dev/default config."""
    if config_path is None:
        config_path = _resolve_data_dir() / "config.json"
    else:
        config_path = Path(config_path)

    if not config_path.exists():
        raise FileNotFoundError(f"Config file not found: {config_path}")

    with open(config_path) as f:
        raw: dict[str, Any] = json.load(f)

    return ObsidianRagConfig(
        vault_path=raw.get("vault_path", ""),
        embedding=_merge(EmbeddingConfig(), raw.get("embedding", {})),
        vector_store=_merge(VectorStoreConfig(), raw.get("vector_store", {})),
        indexing=_merge(IndexingConfig(), raw.get("indexing", {})),
        security=_merge(SecurityConfig(), raw.get("security", {})),
        memory=_merge(MemoryConfig(), raw.get("memory", {})),
    )


def _merge(default: Any, overrides: dict[str, Any]) -> Any:
    """Shallow-merge a dict into a dataclass instance."""
    if not isinstance(default, type) and not isinstance(default, (list, dict, str, int, float, bool)):
        # It's a dataclass instance — merge fields
        if hasattr(default, "__dataclass_fields__"):
            fields = {}
            for key, val in overrides.items():
                if key in default.__dataclass_fields__:
                    field_def = default.__dataclass_fields__[key]
                    actual_default = field_def.default
                    if isinstance(actual_default, type) and issubclass(actual_default, Enum):
                        # Enum fields need special handling
                        fields[key] = val
                    elif isinstance(val, dict):
                        fields[key] = _merge(actual_default, val)
                    else:
                        fields[key] = val
                else:
                    fields[key] = val
            return default.__class__(**{**default.__dict__, **fields})
    if isinstance(overrides, dict) and isinstance(default, dict):
        return {**default, **overrides}
    return overrides if overrides is not None else default


def resolve_vault_path(config: ObsidianRagConfig) -> Path:
    """Resolve vault_path relative to project root or as absolute."""
    vp = Path(config.vault_path)
    if vp.is_absolute():
        return vp
    # Resolve relative to project root
    return (DEFAULT_CONFIG_DIR / vp).resolve()


def resolve_vector_db_path(config: ObsidianRagConfig) -> Path:
    """Resolve vector store path relative to data directory."""
    data_dir = _resolve_data_dir()
    vsp = Path(config.vector_store.path)
    if vsp.is_absolute():
        return vsp
    return (data_dir / vsp).resolve()