//! Database queries for the `settings` table.
//!
//! Uses an upsert pattern: settings are created with defaults on first access
//! and updated in place thereafter.

use sqlx::PgPool;
use uuid::Uuid;

use crate::errors::AppError;
use crate::models::settings::{UpdateSettingsRequest, UserSettings};

/// Row type for settings queries.
#[derive(Debug, sqlx::FromRow)]
struct SettingsRow {
    user_id: Uuid,
    theme: String,
    max_age_days: i32,
    categories: serde_json::Value,
    max_items_per_category: i32,
    search_agent_behavior: String,
    ai_provider: String,
    ai_model: String,
    ai_model_writing: String,
    rate_limit_max_requests: Option<i32>,
    rate_limit_time_window_seconds: Option<i32>,
    updated_at: chrono::DateTime<chrono::Utc>,
}

impl TryFrom<SettingsRow> for UserSettings {
    type Error = AppError;

    fn try_from(row: SettingsRow) -> Result<Self, Self::Error> {
        let categories: Vec<String> = serde_json::from_value(row.categories).map_err(|e| {
            AppError::Internal(anyhow::anyhow!("Failed to parse categories JSON: {}", e))
        })?;

        Ok(Self {
            user_id: row.user_id,
            theme: row.theme,
            max_age_days: row.max_age_days,
            categories,
            max_items_per_category: row.max_items_per_category,
            search_agent_behavior: row.search_agent_behavior,
            ai_provider: row.ai_provider,
            ai_model: row.ai_model,
            ai_model_writing: row.ai_model_writing,
            rate_limit_max_requests: row.rate_limit_max_requests,
            rate_limit_time_window_seconds: row.rate_limit_time_window_seconds,
            updated_at: row.updated_at,
        })
    }
}

/// Get user settings, creating default settings if none exist.
///
/// This ensures that `GET /api/v1/settings` always returns valid settings
/// even for newly created users.
pub async fn get_or_create_default(
    pool: &PgPool,
    user_id: Uuid,
) -> Result<UserSettings, AppError> {
    let defaults = UserSettings::default();
    let categories_json = serde_json::to_value(&defaults.categories).map_err(|e| {
        AppError::Internal(anyhow::anyhow!("Failed to serialize default categories: {}", e))
    })?;

    let row = sqlx::query_as::<_, SettingsRow>(
        r#"
        INSERT INTO settings (user_id, theme, max_age_days, categories, max_items_per_category, search_agent_behavior, ai_provider, ai_model, ai_model_writing, rate_limit_max_requests, rate_limit_time_window_seconds)
        VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11)
        ON CONFLICT (user_id) DO UPDATE SET user_id = settings.user_id
        RETURNING user_id, theme, max_age_days, categories, max_items_per_category, search_agent_behavior, ai_provider, ai_model, ai_model_writing, rate_limit_max_requests, rate_limit_time_window_seconds, updated_at
        "#,
    )
    .bind(user_id)
    .bind(&defaults.theme)
    .bind(defaults.max_age_days)
    .bind(&categories_json)
    .bind(defaults.max_items_per_category)
    .bind(&defaults.search_agent_behavior)
    .bind(&defaults.ai_provider)
    .bind(&defaults.ai_model)
    .bind(&defaults.ai_model_writing)
    .bind(defaults.rate_limit_max_requests)
    .bind(defaults.rate_limit_time_window_seconds)
    .fetch_one(pool)
    .await?;

    UserSettings::try_from(row)
}

/// Update user settings (upsert).
pub async fn upsert(
    pool: &PgPool,
    user_id: Uuid,
    req: &UpdateSettingsRequest,
) -> Result<UserSettings, AppError> {
    let categories_json = serde_json::to_value(&req.categories).map_err(|e| {
        AppError::Internal(anyhow::anyhow!("Failed to serialize categories: {}", e))
    })?;

    let row = sqlx::query_as::<_, SettingsRow>(
        r#"
        INSERT INTO settings (user_id, theme, max_age_days, categories, max_items_per_category, search_agent_behavior, ai_provider, ai_model, ai_model_writing, rate_limit_max_requests, rate_limit_time_window_seconds)
        VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11)
        ON CONFLICT (user_id) DO UPDATE SET
            theme = EXCLUDED.theme,
            max_age_days = EXCLUDED.max_age_days,
            categories = EXCLUDED.categories,
            max_items_per_category = EXCLUDED.max_items_per_category,
            search_agent_behavior = EXCLUDED.search_agent_behavior,
            ai_provider = EXCLUDED.ai_provider,
            ai_model = EXCLUDED.ai_model,
            ai_model_writing = EXCLUDED.ai_model_writing,
            rate_limit_max_requests = EXCLUDED.rate_limit_max_requests,
            rate_limit_time_window_seconds = EXCLUDED.rate_limit_time_window_seconds,
            updated_at = now()
        RETURNING user_id, theme, max_age_days, categories, max_items_per_category, search_agent_behavior, ai_provider, ai_model, ai_model_writing, rate_limit_max_requests, rate_limit_time_window_seconds, updated_at
        "#,
    )
    .bind(user_id)
    .bind(&req.theme)
    .bind(req.max_age_days)
    .bind(&categories_json)
    .bind(req.max_items_per_category)
    .bind(&req.search_agent_behavior)
    .bind(&req.ai_provider)
    .bind(&req.ai_model)
    .bind(&req.ai_model_writing)
    .bind(req.rate_limit_max_requests)
    .bind(req.rate_limit_time_window_seconds)
    .fetch_one(pool)
    .await?;

    UserSettings::try_from(row)
}