//! Core message model — maps to PostgreSQL `message` table.
//!
//! Discord-style: `body` holds plain text / markdown, rich content lives in
//! companion tables (attachment, embed, poll, reaction, mention).
//! IDs are UUID v7 (time-ordered) so `ORDER BY id` = chronological order.

use chrono::{DateTime, Utc};
use serde::{Deserialize, Serialize};
use uuid::Uuid;

/// Discriminator for system / event messages vs. regular user messages.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize, Default)]
#[serde(rename_all = "snake_case")]
pub enum MessageType {
    /// Regular user message (text / markdown).
    #[default]
    Text,
    /// System-generated notice (e.g. "user joined the channel").
    System,
    /// Channel event (pinned a message, changed topic, etc.).
    Event,
    /// Forum article / long-form post displayed as waterfall cards.
    Article,
}

impl MessageType {
    pub fn as_str(&self) -> &'static str {
        match self {
            Self::Text => "text",
            Self::System => "system",
            Self::Event => "event",
            Self::Article => "article",
        }
    }

    pub fn from_str_lossy(s: &str) -> Self {
        match s {
            "system" => Self::System,
            "event" => Self::Event,
            "article" => Self::Article,
            _ => Self::Text,
        }
    }
}

impl std::fmt::Display for MessageType {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.write_str(self.as_str())
    }
}

/// Direct mapping of the `message` table row.
#[derive(Debug, Clone, Serialize, Deserialize, sqlx::FromRow)]
pub struct Message {
    /// UUID v7 — time-ordered primary key.
    pub id: Uuid,
    pub channel_id: Uuid,
    pub author_id: Uuid,
    /// Thread this message belongs to (NULL = not threaded).
    pub thread_id: Option<Uuid>,
    /// Direct reply reference (NULL = top-level message).
    pub reply_to_message_id: Option<Uuid>,
    /// "text" | "system" | "event"
    pub message_type: String,
    /// Plain text or markdown body.
    pub body: String,
    /// Extensible metadata (flags, locale, interaction ref, etc.).
    pub metadata: Option<serde_json::Value>,
    pub pinned: bool,
    /// True for bot / system generated messages.
    pub system: bool,
    pub edited_at: Option<DateTime<Utc>>,
    pub deleted_at: Option<DateTime<Utc>>,
    pub created_at: DateTime<Utc>,
    pub updated_at: DateTime<Utc>,
}

/// Lightweight author info embedded in [`MessageDetail`].
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct AuthorInfo {
    pub id: Uuid,
    pub username: String,
    pub display_name: Option<String>,
    pub avatar_url: Option<String>,
    pub is_bot: bool,
}

/// Message with resolved author and reaction/attachment aggregates.
/// Returned by read APIs; never stored directly.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct MessageDetail {
    #[serde(flatten)]
    pub message: Message,
    pub author: AuthorInfo,
    /// Aggregated reaction counts: `{ "👍": 3, "🎉": 1 }`.
    pub reactions: std::collections::HashMap<String, i64>,
    pub attachment_count: i64,
    pub embed_count: i64,
    /// Whether the current user has bookmarked this message.
    pub bookmarked: bool,
    /// Reply chain depth (0 = top-level).
    pub reply_depth: i32,
}

/// Generate a new UUID v7 (time-ordered) for message IDs.
pub fn new_message_id() -> Uuid {
    Uuid::now_v7()
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_message_type_roundtrip() {
        let t = MessageType::Text;
        assert_eq!(t.as_str(), "text");
        assert_eq!(MessageType::from_str_lossy("text"), MessageType::Text);
        assert_eq!(MessageType::from_str_lossy("system"), MessageType::System);
        assert_eq!(MessageType::from_str_lossy("unknown"), MessageType::Text);
    }

    #[test]
    fn test_message_id_ordering() {
        // UUID v7 IDs generated later should sort after earlier ones.
        let a = new_message_id();
        std::thread::sleep(std::time::Duration::from_millis(2));
        let b = new_message_id();
        assert!(b > a, "UUID v7 should be time-ordered");
    }

    #[test]
    fn test_message_detail_serialize() {
        let msg = Message {
            id: Uuid::now_v7(),
            channel_id: Uuid::now_v7(),
            author_id: Uuid::now_v7(),
            thread_id: None,
            reply_to_message_id: None,
            message_type: "text".to_string(),
            body: "hello world".to_string(),
            metadata: None,
            pinned: false,
            system: false,
            edited_at: None,
            deleted_at: None,
            created_at: Utc::now(),
            updated_at: Utc::now(),
        };

        let detail = MessageDetail {
            message: msg,
            author: AuthorInfo {
                id: Uuid::now_v7(),
                username: "alice".to_string(),
                display_name: Some("Alice".to_string()),
                avatar_url: None,
                is_bot: false,
            },
            reactions: std::collections::HashMap::from([
                ("👍".to_string(), 3),
                ("🎉".to_string(), 1),
            ]),
            attachment_count: 0,
            embed_count: 0,
            bookmarked: false,
            reply_depth: 0,
        };

        let json = serde_json::to_value(&detail).unwrap();
        assert_eq!(json["body"], "hello world");
        assert_eq!(json["author"]["username"], "alice");
        assert_eq!(json["reactions"]["👍"], 3);
    }
}