//! Shared helpers for database adapter crates (SQLite, PostgreSQL).
//!
//! Provides error mapping, datetime parsing, UUID parsing, and JSON
//! deserialization helpers that are identical across database backends.

use chrono::{DateTime, Utc};
use domain::{DomainError, RecyclePolicy, ScheduleConfig, ScheduleConfigCompat};
use serde::de::DeserializeOwned;
use uuid::Uuid;

// ============================================================================
// Error mapping
// ============================================================================

/// Map a [`sqlx::Error`] into a [`DomainError::RepositoryError`].
pub fn map_sqlx_error(err: sqlx::Error) -> DomainError {
    tracing::error!(error = %err, "database error");
    DomainError::RepositoryError(err.to_string())
}

// ============================================================================
// Datetime parsing
// ============================================================================

/// Parse a datetime string stored in the database.
///
/// Tries RFC 3339 first (e.g. `2026-03-19T00:00:00Z`), then falls back to
/// the bare SQLite format `%Y-%m-%d %H:%M:%S` (no timezone, assumed UTC).
pub fn parse_dt(s: &str) -> Result<DateTime<Utc>, DomainError> {
    DateTime::parse_from_rfc3339(s)
        .map(|dt| dt.with_timezone(&Utc))
        .or_else(|_| {
            chrono::NaiveDateTime::parse_from_str(s, "%Y-%m-%d %H:%M:%S").map(|dt| dt.and_utc())
        })
        .map_err(|e| DomainError::RepositoryError(format!("Invalid datetime '{}': {}", s, e)))
}

// ============================================================================
// UUID parsing
// ============================================================================

/// Parse a UUID string from the database, wrapping errors in [`DomainError::RepositoryError`].
///
/// The `context` parameter is included in the error message for diagnostics
/// (e.g. `"channel id"`, `"slot id"`).
pub fn parse_uuid(s: &str, context: &str) -> Result<Uuid, DomainError> {
    Uuid::parse_str(s)
        .map_err(|e| DomainError::RepositoryError(format!("Invalid {} UUID '{}': {}", context, s, e)))
}

// ============================================================================
// JSON deserialization helpers
// ============================================================================

/// Deserialize a JSON string from the database into `T`.
///
/// The `context` parameter is included in the error message for diagnostics
/// (e.g. `"schedule_config"`, `"slot item"`).
pub fn parse_json<T: DeserializeOwned>(json: &str, context: &str) -> Result<T, DomainError> {
    serde_json::from_str(json)
        .map_err(|e| DomainError::RepositoryError(format!("Invalid {} JSON: {}", context, e)))
}

/// Parse a `schedule_config` JSON column, handling V1/V2 compat migration.
pub fn parse_schedule_config(json: &str) -> Result<ScheduleConfig, DomainError> {
    let compat: ScheduleConfigCompat = parse_json(json, "schedule_config")?;
    Ok(ScheduleConfig::from(compat))
}

/// Parse a `recycle_policy` JSON column.
pub fn parse_recycle_policy(json: &str) -> Result<RecyclePolicy, DomainError> {
    parse_json(json, "recycle_policy")
}

/// Deserialize a string-encoded enum, returning `T::default()` on failure.
///
/// Used for columns like `access_mode` and `logo_position` that are stored as
/// bare strings (e.g. `"public"`, `"top_left"`) and deserialized via serde.
pub fn parse_enum_or_default<T: DeserializeOwned + Default>(value: String) -> T {
    serde_json::from_value(serde_json::Value::String(value)).unwrap_or_default()
}

// ============================================================================
// Tests
// ============================================================================

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

    #[test]
    fn parse_dt_rfc3339() {
        let dt = parse_dt("2026-03-19T12:30:00Z").unwrap();
        assert_eq!(dt.year(), 2026);
        assert_eq!(dt.month(), 3);
        assert_eq!(dt.day(), 19);
    }

    #[test]
    fn parse_dt_sqlite_format() {
        let dt = parse_dt("2026-03-19 12:30:00").unwrap();
        assert_eq!(dt.year(), 2026);
    }

    #[test]
    fn parse_dt_invalid() {
        assert!(parse_dt("not-a-date").is_err());
    }

    #[test]
    fn parse_uuid_valid() {
        let u = Uuid::new_v4();
        let parsed = parse_uuid(&u.to_string(), "test").unwrap();
        assert_eq!(parsed, u);
    }

    #[test]
    fn parse_uuid_invalid() {
        let err = parse_uuid("not-a-uuid", "channel id").unwrap_err();
        let msg = err.to_string();
        assert!(msg.contains("channel id"), "error should contain context: {msg}");
    }

    #[test]
    fn parse_json_valid() {
        let val: Vec<i32> = parse_json("[1,2,3]", "test").unwrap();
        assert_eq!(val, vec![1, 2, 3]);
    }

    #[test]
    fn parse_json_invalid() {
        let err = parse_json::<Vec<i32>>("not json", "test_field").unwrap_err();
        let msg = err.to_string();
        assert!(msg.contains("test_field"), "error should contain context: {msg}");
    }

    #[test]
    fn parse_schedule_config_v2() {
        let json = r#"{"day_blocks":{}}"#;
        let cfg = parse_schedule_config(json).unwrap();
        assert!(cfg.day_blocks().is_empty());
    }

    #[test]
    fn parse_schedule_config_v1_compat() {
        let json = r#"{"blocks":[]}"#;
        let cfg = parse_schedule_config(json).unwrap();
        // V1 promotes blocks to all 7 days
        assert_eq!(cfg.day_blocks().len(), 7);
    }

    #[test]
    fn parse_recycle_policy_valid() {
        let json = r#"{"cooldown_days":7,"cooldown_generations":3,"min_available_ratio":0.3}"#;
        let policy = parse_recycle_policy(json).unwrap();
        assert_eq!(policy.cooldown_days, Some(7));
    }

    #[test]
    fn parse_enum_or_default_valid() {
        use domain::AccessMode;
        let mode: AccessMode = parse_enum_or_default("public".to_string());
        assert!(matches!(mode, AccessMode::Public));
    }

    #[test]
    fn parse_enum_or_default_fallback() {
        use domain::AccessMode;
        let mode: AccessMode = parse_enum_or_default("garbage".to_string());
        // Should return default (Public)
        assert!(matches!(mode, AccessMode::Public));
    }

    #[test]
    fn map_sqlx_error_produces_repository_error() {
        let sqlx_err = sqlx::Error::RowNotFound;
        let domain_err = map_sqlx_error(sqlx_err);
        assert!(matches!(domain_err, DomainError::RepositoryError(_)));
    }
}