//! User settings model.

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

/// User settings record from the database.
#[derive(Debug, Clone, Serialize)]
pub struct UserSettings {
    pub user_id: Uuid,
    pub theme: String,
    pub max_age_days: i32,
    pub categories: Vec<String>,
    pub max_items_per_category: i32,
    pub search_agent_behavior: String,
    pub updated_at: DateTime<Utc>,
}

/// Response shape for `GET /api/v1/settings`.
#[derive(Debug, Serialize)]
pub struct SettingsResponse {
    pub theme: String,
    pub max_age_days: i32,
    pub categories: Vec<String>,
    pub max_items_per_category: i32,
    pub search_agent_behavior: String,
}

/// Request body for `PUT /api/v1/settings`.
#[derive(Debug, Deserialize)]
pub struct UpdateSettingsRequest {
    pub theme: String,
    pub max_age_days: i32,
    pub categories: Vec<String>,
    pub max_items_per_category: i32,
    pub search_agent_behavior: String,
}

impl UpdateSettingsRequest {
    /// Validate the settings update request.
    ///
    /// Returns `Ok(())` if all fields are within acceptable bounds,
    /// or `Err(message)` describing the first validation failure.
    pub fn validate(&self) -> Result<(), String> {
        if self.theme.trim().is_empty() {
            return Err("Theme cannot be empty".into());
        }
        if self.theme.len() > 200 {
            return Err("Theme must be at most 200 characters".into());
        }
        if !(1..=365).contains(&self.max_age_days) {
            return Err("max_age_days must be between 1 and 365".into());
        }
        if self.categories.is_empty() {
            return Err("Categories cannot be empty".into());
        }
        if self.categories.len() > 20 {
            return Err("At most 20 categories are allowed".into());
        }
        for (i, cat) in self.categories.iter().enumerate() {
            if cat.trim().is_empty() {
                return Err(format!("Category at index {} cannot be empty", i));
            }
            if cat.len() > 200 {
                return Err(format!(
                    "Category at index {} must be at most 200 characters",
                    i
                ));
            }
        }
        if !(1..=50).contains(&self.max_items_per_category) {
            return Err("max_items_per_category must be between 1 and 50".into());
        }
        if self.search_agent_behavior.len() > 2000 {
            return Err("search_agent_behavior must be at most 2000 characters".into());
        }
        Ok(())
    }
}

/// Default settings values used when a user has no saved settings.
impl Default for UserSettings {
    fn default() -> Self {
        Self {
            user_id: Uuid::nil(),
            theme: "Intelligence Artificielle".to_string(),
            max_age_days: 7,
            categories: vec![
                "Annonces majeures".to_string(),
                "Recherche et innovation".to_string(),
                "Industrie et entreprises".to_string(),
                "Secteur public".to_string(),
                "Opinions et analyses".to_string(),
            ],
            max_items_per_category: 4,
            search_agent_behavior: String::new(),
            updated_at: Utc::now(),
        }
    }
}

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

    #[test]
    fn test_valid_settings() {
        let req = UpdateSettingsRequest {
            theme: "Intelligence Artificielle".into(),
            max_age_days: 7,
            categories: vec!["Category 1".into(), "Category 2".into()],
            max_items_per_category: 4,
            search_agent_behavior: String::new(),
        };
        assert!(req.validate().is_ok());
    }

    #[test]
    fn test_empty_theme() {
        let req = UpdateSettingsRequest {
            theme: "   ".into(),
            max_age_days: 7,
            categories: vec!["Cat".into()],
            max_items_per_category: 4,
            search_agent_behavior: String::new(),
        };
        let err = req.validate().unwrap_err();
        assert!(err.contains("Theme"));
    }

    #[test]
    fn test_theme_too_long() {
        let req = UpdateSettingsRequest {
            theme: "a".repeat(201),
            max_age_days: 7,
            categories: vec!["Cat".into()],
            max_items_per_category: 4,
            search_agent_behavior: String::new(),
        };
        assert!(req.validate().is_err());
    }

    #[test]
    fn test_max_age_days_below_range() {
        let req = UpdateSettingsRequest {
            theme: "AI".into(),
            max_age_days: 0,
            categories: vec!["Cat".into()],
            max_items_per_category: 4,
            search_agent_behavior: String::new(),
        };
        let err = req.validate().unwrap_err();
        assert!(err.contains("max_age_days"));
    }

    #[test]
    fn test_max_age_days_above_range() {
        let req = UpdateSettingsRequest {
            theme: "AI".into(),
            max_age_days: 366,
            categories: vec!["Cat".into()],
            max_items_per_category: 4,
            search_agent_behavior: String::new(),
        };
        assert!(req.validate().is_err());
    }

    #[test]
    fn test_empty_categories() {
        let req = UpdateSettingsRequest {
            theme: "AI".into(),
            max_age_days: 7,
            categories: vec![],
            max_items_per_category: 4,
            search_agent_behavior: String::new(),
        };
        let err = req.validate().unwrap_err();
        assert!(err.contains("Categories"));
    }

    #[test]
    fn test_too_many_categories() {
        let cats: Vec<String> = (0..21).map(|i| format!("Cat {}", i)).collect();
        let req = UpdateSettingsRequest {
            theme: "AI".into(),
            max_age_days: 7,
            categories: cats,
            max_items_per_category: 4,
            search_agent_behavior: String::new(),
        };
        let err = req.validate().unwrap_err();
        assert!(err.contains("20"));
    }

    #[test]
    fn test_empty_category_item() {
        let req = UpdateSettingsRequest {
            theme: "AI".into(),
            max_age_days: 7,
            categories: vec!["Good".into(), "  ".into()],
            max_items_per_category: 4,
            search_agent_behavior: String::new(),
        };
        let err = req.validate().unwrap_err();
        assert!(err.contains("index 1"));
    }

    #[test]
    fn test_max_items_below_range() {
        let req = UpdateSettingsRequest {
            theme: "AI".into(),
            max_age_days: 7,
            categories: vec!["Cat".into()],
            max_items_per_category: 0,
            search_agent_behavior: String::new(),
        };
        assert!(req.validate().is_err());
    }

    #[test]
    fn test_max_items_above_range() {
        let req = UpdateSettingsRequest {
            theme: "AI".into(),
            max_age_days: 7,
            categories: vec!["Cat".into()],
            max_items_per_category: 51,
            search_agent_behavior: String::new(),
        };
        assert!(req.validate().is_err());
    }

    #[test]
    fn test_search_agent_behavior_too_long() {
        let req = UpdateSettingsRequest {
            theme: "AI".into(),
            max_age_days: 7,
            categories: vec!["Cat".into()],
            max_items_per_category: 4,
            search_agent_behavior: "a".repeat(2001),
        };
        assert!(req.validate().is_err());
    }

    #[test]
    fn test_boundary_values_valid() {
        let req = UpdateSettingsRequest {
            theme: "A".into(),
            max_age_days: 1,
            categories: vec!["Cat".into()],
            max_items_per_category: 1,
            search_agent_behavior: String::new(),
        };
        assert!(req.validate().is_ok());

        let req = UpdateSettingsRequest {
            theme: "A".into(),
            max_age_days: 365,
            categories: (0..20).map(|i| format!("Cat {}", i)).collect(),
            max_items_per_category: 50,
            search_agent_behavior: "a".repeat(2000),
        };
        assert!(req.validate().is_ok());
    }
}