//! Draft CRUD operations on `MessageRepo`.
//!
//! One draft per (channel, user, thread). Upserted on every keystroke debounce,
//! deleted on send. Thread_id=NULL uses a dedicated conflict target.

use chrono::Utc;
use uuid::Uuid;

use crate::ImksResult;
use crate::models::message_draft::MessageDraft;

use super::message_repo::MessageRepo;

impl MessageRepo {
    /// Upsert a draft for the given (channel, user, thread) key.
    /// Uses NULL-safe conflict handling via COALESCE.
    pub async fn upsert_draft(
        &self,
        channel_id: Uuid,
        user_id: Uuid,
        thread_id: Option<Uuid>,
        body: &str,
        reply_to_message_id: Option<Uuid>,
        metadata: Option<serde_json::Value>,
    ) -> ImksResult<MessageDraft> {
        let id = Uuid::now_v7();
        let now = Utc::now();

        let query = if thread_id.is_some() {
            r#"
            INSERT INTO message_draft (
                id, channel_id, user_id, thread_id, reply_to_message_id,
                body, metadata, created_at, updated_at
            ) VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $8)
            ON CONFLICT (channel_id, user_id, thread_id) DO UPDATE SET
                body = EXCLUDED.body,
                reply_to_message_id = EXCLUDED.reply_to_message_id,
                metadata = EXCLUDED.metadata,
                updated_at = EXCLUDED.updated_at
            RETURNING *
            "#
        } else {
            r#"
            INSERT INTO message_draft (
                id, channel_id, user_id, thread_id, reply_to_message_id,
                body, metadata, created_at, updated_at
            ) VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $8)
            ON CONFLICT (channel_id, user_id) WHERE thread_id IS NULL DO UPDATE SET
                body = EXCLUDED.body,
                reply_to_message_id = EXCLUDED.reply_to_message_id,
                metadata = EXCLUDED.metadata,
                updated_at = EXCLUDED.updated_at
            RETURNING *
            "#
        };

        sqlx::query_as::<_, MessageDraft>(query)
            .bind(id)
            .bind(channel_id)
            .bind(user_id)
            .bind(thread_id)
            .bind(reply_to_message_id)
            .bind(body)
            .bind(metadata)
            .bind(now)
            .fetch_one(self.pool())
            .await
            .map_err(Into::into)
    }

    /// Get a user's draft for a channel (optionally scoped to a thread).
    pub async fn get_draft(
        &self,
        channel_id: Uuid,
        user_id: Uuid,
        thread_id: Option<Uuid>,
    ) -> ImksResult<Option<MessageDraft>> {
        sqlx::query_as::<_, MessageDraft>(
            r#"
            SELECT * FROM message_draft
            WHERE channel_id = $1 AND user_id = $2 AND thread_id IS NOT DISTINCT FROM $3
            "#,
        )
        .bind(channel_id)
        .bind(user_id)
        .bind(thread_id)
        .fetch_optional(self.pool())
        .await
        .map_err(Into::into)
    }

    /// Delete a draft after the message is sent.
    pub async fn delete_draft(
        &self,
        channel_id: Uuid,
        user_id: Uuid,
        thread_id: Option<Uuid>,
    ) -> ImksResult<bool> {
        let result = sqlx::query(
            r#"
            DELETE FROM message_draft
            WHERE channel_id = $1 AND user_id = $2 AND thread_id IS NOT DISTINCT FROM $3
            "#,
        )
        .bind(channel_id)
        .bind(user_id)
        .bind(thread_id)
        .execute(self.pool())
        .await?;

        Ok(result.rows_affected() > 0)
    }
}