"""Configuration system for Mail email reader using Pydantic."""

import logging
import os
from pathlib import Path
from typing import Literal, Optional

import toml
from pydantic import BaseModel, Field

logger = logging.getLogger(__name__)


class TaskBackendConfig(BaseModel):
    """Configuration for task management backend."""

    backend: Literal["taskwarrior", "dstask"] = "taskwarrior"
    taskwarrior_path: str = "task"
    dstask_path: str = Field(
        default_factory=lambda: str(Path.home() / ".local" / "bin" / "dstask")
    )


class EnvelopeDisplayConfig(BaseModel):
    """Configuration for envelope list item rendering."""

    # Sender display
    max_sender_length: int = 25

    # Date/time display
    date_format: str = "%m/%d"
    time_format: str = "%H:%M"
    show_date: bool = True
    show_time: bool = True

    # Grouping
    group_by: Literal["relative", "absolute"] = "relative"
    # relative: "Today", "Yesterday", "This Week", etc.
    # absolute: "December 2025", "November 2025", etc.

    # Layout
    lines: Literal[2, 3] = 2
    # 2: sender/date on line 1, subject on line 2
    # 3: sender/date on line 1, subject on line 2, preview on line 3

    show_checkbox: bool = True
    show_preview: bool = False  # Only used when lines=3

    # NerdFont icons for status
    icon_unread: str = "\uf0e0"  # nf-fa-envelope (filled)
    icon_read: str = "\uf2b6"  # nf-fa-envelope_open (open)
    icon_flagged: str = "\uf024"  # nf-fa-flag
    icon_attachment: str = "\uf0c6"  # nf-fa-paperclip


class KeybindingsConfig(BaseModel):
    """Keybinding customization."""

    next_message: str = "j"
    prev_message: str = "k"
    delete: str = "#"
    archive: str = "e"
    open_by_id: str = "o"
    quit: str = "q"
    toggle_header: str = "h"
    create_task: str = "t"
    reload: str = "%"
    toggle_sort: str = "s"
    toggle_selection: str = "space"
    clear_selection: str = "escape"
    scroll_page_down: str = "pagedown"
    scroll_page_down: str = "space"
    scroll_page_up: str = "b"
    toggle_main_content: str = "w"
    open_links: str = "l"
    toggle_view_mode: str = "m"


class ContentDisplayConfig(BaseModel):
    """Configuration for message content display."""

    # View mode: "markdown" for pretty rendering, "html" for raw/plain display
    default_view_mode: Literal["markdown", "html"] = "markdown"


class LinkPanelConfig(BaseModel):
    """Configuration for the link panel."""

    # Whether to close the panel after opening a link
    close_on_open: bool = False


class MailOperationsConfig(BaseModel):
    """Configuration for mail operations."""

    # Folder to move messages to when archiving
    archive_folder: str = "Archive"


class ThemeConfig(BaseModel):
    """Theme/appearance settings."""

    theme_name: str = "monokai"


class MailAppConfig(BaseModel):
    """Main configuration for Mail email reader."""

    task: TaskBackendConfig = Field(default_factory=TaskBackendConfig)
    envelope_display: EnvelopeDisplayConfig = Field(
        default_factory=EnvelopeDisplayConfig
    )
    content_display: ContentDisplayConfig = Field(default_factory=ContentDisplayConfig)
    link_panel: LinkPanelConfig = Field(default_factory=LinkPanelConfig)
    mail: MailOperationsConfig = Field(default_factory=MailOperationsConfig)
    keybindings: KeybindingsConfig = Field(default_factory=KeybindingsConfig)
    theme: ThemeConfig = Field(default_factory=ThemeConfig)

    @classmethod
    def get_config_path(cls) -> Path:
        """Get the path to the config file."""
        # Check environment variable first
        env_path = os.getenv("LUK_MAIL_CONFIG")
        if env_path:
            return Path(env_path)

        # Default to ~/.config/luk/mail.toml
        return Path.home() / ".config" / "luk" / "mail.toml"

    @classmethod
    def load(cls, config_path: Optional[Path] = None) -> "MailAppConfig":
        """Load config from TOML file with defaults for missing values."""
        if config_path is None:
            config_path = cls.get_config_path()

        if config_path.exists():
            try:
                with open(config_path, "r") as f:
                    data = toml.load(f)
                logger.info(f"Loaded config from {config_path}")
                return cls.model_validate(data)
            except Exception as e:
                logger.warning(f"Error loading config from {config_path}: {e}")
                logger.warning("Using default configuration")
                return cls()
        else:
            logger.info(f"No config file at {config_path}, using defaults")
            return cls()

    def save(self, config_path: Optional[Path] = None) -> None:
        """Save current config to TOML file."""
        if config_path is None:
            config_path = self.get_config_path()

        # Ensure parent directory exists
        config_path.parent.mkdir(parents=True, exist_ok=True)

        with open(config_path, "w") as f:
            toml.dump(self.model_dump(), f)
        logger.info(f"Saved config to {config_path}")


# Global config instance (lazy-loaded)
_config: Optional[MailAppConfig] = None


def get_config() -> MailAppConfig:
    """Get the global config instance, loading it if necessary."""
    global _config
    if _config is None:
        _config = MailAppConfig.load()
    return _config


def reload_config() -> MailAppConfig:
    """Force reload of the config from disk."""
    global _config
    _config = MailAppConfig.load()
    return _config