use std::collections::HashMap;
use std::sync::Arc;

use nomifun_api_types::{CreateProviderRequest, ProviderResponse, UpdateProviderRequest};
use nomifun_common::{AppError, decrypt_string, encrypt_string};
use nomifun_db::{CreateProviderParams, IProviderRepository, UpdateProviderParams, models::Provider};
use serde::de::DeserializeOwned;

/// Business logic for model provider CRUD with API key encryption/masking.
#[derive(Clone)]
pub struct ProviderService {
    repo: Arc<dyn IProviderRepository>,
    encryption_key: [u8; 32],
}

impl ProviderService {
    pub fn new(repo: Arc<dyn IProviderRepository>, encryption_key: [u8; 32]) -> Self {
        Self { repo, encryption_key }
    }

    /// List all providers with masked API keys.
    pub async fn list(&self) -> Result<Vec<ProviderResponse>, AppError> {
        let rows = self.repo.list().await?;
        rows.into_iter().map(|row| self.row_to_response(row)).collect()
    }

    /// Create a new provider. The API key is encrypted before storage.
    ///
    /// If `req.id` is `Some`, the caller-supplied id is used (after validation);
    /// otherwise a fresh id is generated by the repository. This supports the
    /// frontend-local-store → backend migration path where existing provider
    /// ids must be preserved.
    pub async fn create(&self, req: CreateProviderRequest) -> Result<ProviderResponse, AppError> {
        validate_create_request(&req)?;

        let encrypted_key = encrypt_string(&req.api_key, &self.encryption_key)?;
        let models_json = serialize_json(&req.models, "models")?;
        let capabilities_json = serialize_json(&req.capabilities, "capabilities")?;
        let model_protocols_json = serialize_opt(&req.model_protocols, "model_protocols")?;
        let model_enabled_json = serialize_opt(&req.model_enabled, "model_enabled")?;
        let model_health_json = serialize_opt(&req.model_health, "model_health")?;
        let bedrock_json = serialize_opt(&req.bedrock_config, "bedrock_config")?;
        let trimmed_id = req.id.as_deref().map(str::trim);

        let params = CreateProviderParams {
            id: trimmed_id,
            platform: &req.platform,
            name: &req.name,
            base_url: &req.base_url,
            api_key_encrypted: &encrypted_key,
            models: &models_json,
            enabled: req.enabled,
            capabilities: &capabilities_json,
            context_limit: req.context_limit,
            model_protocols: model_protocols_json.as_deref(),
            model_enabled: model_enabled_json.as_deref(),
            model_health: model_health_json.as_deref(),
            bedrock_config: bedrock_json.as_deref(),
            is_full_url: req.is_full_url,
        };

        let row = self.repo.create(params).await?;
        self.row_to_response(row)
    }

    /// Update an existing provider. Only provided fields are changed.
    pub async fn update(&self, id: &str, req: UpdateProviderRequest) -> Result<ProviderResponse, AppError> {
        validate_update_request(&req)?;

        let encrypted_key = req
            .api_key
            .as_deref()
            .map(|k| encrypt_string(k, &self.encryption_key))
            .transpose()?;
        let models_json = serialize_opt(&req.models, "models")?;
        let capabilities_json = serialize_opt(&req.capabilities, "capabilities")?;
        let model_protocols_json = serialize_opt(&req.model_protocols, "model_protocols")?;
        let model_enabled_json = serialize_opt(&req.model_enabled, "model_enabled")?;
        let model_health_json = serialize_opt(&req.model_health, "model_health")?;
        let bedrock_json = serialize_opt(&req.bedrock_config, "bedrock_config")?;

        let params = UpdateProviderParams {
            platform: req.platform.as_deref(),
            name: req.name.as_deref(),
            base_url: req.base_url.as_deref(),
            api_key_encrypted: encrypted_key.as_deref(),
            models: models_json.as_deref(),
            enabled: req.enabled,
            capabilities: capabilities_json.as_deref(),
            context_limit: req.context_limit.map(Some),
            model_protocols: model_protocols_json.as_ref().map(|s| Some(s.as_str())),
            model_enabled: model_enabled_json.as_ref().map(|s| Some(s.as_str())),
            model_health: model_health_json.as_ref().map(|s| Some(s.as_str())),
            bedrock_config: bedrock_json.as_ref().map(|s| Some(s.as_str())),
            is_full_url: req.is_full_url,
        };

        let row = self.repo.update(id, params).await?;
        self.row_to_response(row)
    }

    /// Delete a provider by ID.
    pub async fn delete(&self, id: &str) -> Result<(), AppError> {
        self.repo.delete(id).await?;
        Ok(())
    }

    // -----------------------------------------------------------------------
    // Internal helpers
    // -----------------------------------------------------------------------

    /// Convert a DB row into a response DTO with the plaintext API key
    /// (decrypted) and deserialized JSON fields.
    ///
    /// Pre-launch: the response returns the API key in plaintext so the
    /// frontend can migrate its local store to the backend without losing
    /// the key on re-read. Storage remains encrypted at rest.
    fn row_to_response(&self, row: Provider) -> Result<ProviderResponse, AppError> {
        let api_key = decrypt_string(&row.api_key_encrypted, &self.encryption_key)?;

        let models: Vec<String> = serde_json::from_str(&row.models)
            .map_err(|e| AppError::Internal(format!("Failed to parse models JSON: {e}")))?;
        let capabilities = serde_json::from_str(&row.capabilities)
            .map_err(|e| AppError::Internal(format!("Failed to parse capabilities JSON: {e}")))?;
        let model_protocols: Option<HashMap<String, String>> =
            deserialize_opt(&row.model_protocols, "model_protocols")?;
        let model_enabled: Option<HashMap<String, bool>> = deserialize_opt(&row.model_enabled, "model_enabled")?;
        let model_health = deserialize_opt(&row.model_health, "model_health")?;
        let bedrock_config = deserialize_opt(&row.bedrock_config, "bedrock_config")?;

        Ok(ProviderResponse {
            id: row.id,
            platform: row.platform,
            name: row.name,
            base_url: row.base_url,
            api_key,
            models,
            enabled: row.enabled,
            capabilities,
            context_limit: row.context_limit,
            model_protocols,
            model_enabled,
            model_health,
            bedrock_config,
            is_full_url: row.is_full_url,
            created_at: row.created_at,
            updated_at: row.updated_at,
        })
    }
}

// ---------------------------------------------------------------------------
// JSON helpers (M-1 / M-2 refactor)
// ---------------------------------------------------------------------------

/// Serialize an optional value to JSON string.
fn serialize_opt<T: serde::Serialize>(val: &Option<T>, field: &str) -> Result<Option<String>, AppError> {
    val.as_ref()
        .map(serde_json::to_string)
        .transpose()
        .map_err(|e| AppError::Internal(format!("Failed to serialize {field}: {e}")))
}

/// Serialize a value to JSON string.
fn serialize_json<T: serde::Serialize>(val: &T, field: &str) -> Result<String, AppError> {
    serde_json::to_string(val).map_err(|e| AppError::Internal(format!("Failed to serialize {field}: {e}")))
}

/// Deserialize an optional JSON string into a typed value.
pub(crate) fn deserialize_opt<T: DeserializeOwned>(json: &Option<String>, field: &str) -> Result<Option<T>, AppError> {
    json.as_deref()
        .map(serde_json::from_str)
        .transpose()
        .map_err(|e| AppError::Internal(format!("Failed to parse {field} JSON: {e}")))
}

// ---------------------------------------------------------------------------
// Validation helpers
// ---------------------------------------------------------------------------

fn validate_create_request(req: &CreateProviderRequest) -> Result<(), AppError> {
    if let Some(ref id) = req.id {
        validate_id(id)?;
    }
    if req.platform.trim().is_empty() {
        return Err(AppError::BadRequest("platform is required".into()));
    }
    if req.name.trim().is_empty() {
        return Err(AppError::BadRequest("name is required".into()));
    }
    // Bedrock auths via bedrock_config (IAM profile / static keys) rather than
    // an HTTP endpoint + bearer key, so baseUrl and apiKey may be empty.
    if req.platform == "bedrock" {
        if req.bedrock_config.is_none() {
            return Err(AppError::BadRequest(
                "bedrockConfig is required for bedrock platform".into(),
            ));
        }
        if !req.base_url.trim().is_empty() {
            validate_base_url(&req.base_url)?;
        }
    } else {
        validate_base_url(&req.base_url)?;
        if req.api_key.trim().is_empty() {
            return Err(AppError::BadRequest("apiKey is required".into()));
        }
    }
    Ok(())
}

/// Validate a caller-supplied provider id.
///
/// Accepts any non-empty string up to 128 chars consisting of alphanumerics,
/// dash, or underscore. This is deliberately permissive to accommodate both
/// UUID v4/v7 and legacy short hex ids from the pre-migration frontend.
fn validate_id(id: &str) -> Result<(), AppError> {
    let trimmed = id.trim();
    if trimmed.is_empty() {
        return Err(AppError::BadRequest("id must not be empty".into()));
    }
    if trimmed.len() > 128 {
        return Err(AppError::BadRequest("id must be at most 128 characters".into()));
    }
    if !trimmed
        .chars()
        .all(|c| c.is_ascii_alphanumeric() || c == '-' || c == '_')
    {
        return Err(AppError::BadRequest(
            "id may only contain alphanumerics, '-', or '_'".into(),
        ));
    }
    Ok(())
}

fn validate_update_request(req: &UpdateProviderRequest) -> Result<(), AppError> {
    if let Some(ref platform) = req.platform
        && platform.trim().is_empty()
    {
        return Err(AppError::BadRequest("platform cannot be empty".into()));
    }
    if let Some(ref name) = req.name
        && name.trim().is_empty()
    {
        return Err(AppError::BadRequest("name cannot be empty".into()));
    }
    if let Some(ref url) = req.base_url
        && !url.trim().is_empty()
    {
        validate_base_url(url)?;
    }
    Ok(())
}

fn validate_base_url(url: &str) -> Result<(), AppError> {
    if url.trim().is_empty() {
        return Err(AppError::BadRequest("baseUrl is required".into()));
    }
    if !url.starts_with("http://") && !url.starts_with("https://") {
        return Err(AppError::BadRequest(
            "baseUrl must start with http:// or https://".into(),
        ));
    }
    Ok(())
}

#[cfg(test)]
mod tests {
    use super::*;
    use nomifun_db::{SqliteProviderRepository, init_database_memory};

    // A fixed 32-byte key for testing
    const TEST_KEY: [u8; 32] = [0x42; 32];

    async fn setup() -> ProviderService {
        let db = init_database_memory().await.unwrap();
        let repo = Arc::new(SqliteProviderRepository::new(db.pool().clone()));
        std::mem::forget(db);
        ProviderService::new(repo, TEST_KEY)
    }

    fn sample_create_request() -> CreateProviderRequest {
        CreateProviderRequest {
            id: None,
            platform: "anthropic".into(),
            name: "Anthropic".into(),
            base_url: "https://api.anthropic.com".into(),
            api_key: "sk-ant-api03-test1234".into(),
            models: vec!["claude-sonnet-4-20250514".into()],
            enabled: true,
            capabilities: vec![],
            context_limit: None,
            model_protocols: None,
            model_enabled: None,
            model_health: None,
            bedrock_config: None,
            is_full_url: false,
        }
    }

    // -- id validation tests --

    #[test]
    fn validate_id_accepts_uuid_v4() {
        assert!(validate_id("11111111-1111-4111-8111-111111111111").is_ok());
    }

    #[test]
    fn validate_id_accepts_short_hex() {
        // Frontend's default uuid() yields an 8-char hex string.
        assert!(validate_id("a1b2c3d4").is_ok());
    }

    #[test]
    fn validate_id_accepts_underscore_and_dash() {
        assert!(validate_id("prov_01-foo-bar").is_ok());
    }

    #[test]
    fn validate_id_rejects_empty() {
        assert!(validate_id("").is_err());
        assert!(validate_id("   ").is_err());
    }

    #[test]
    fn validate_id_rejects_too_long() {
        let long = "a".repeat(129);
        assert!(validate_id(&long).is_err());
    }

    #[test]
    fn validate_id_rejects_disallowed_chars() {
        assert!(validate_id("bad/slash").is_err());
        assert!(validate_id("bad space").is_err());
        assert!(validate_id("bad.dot").is_err());
    }

    // -- validation tests --

    #[test]
    fn validate_create_missing_platform() {
        let req = CreateProviderRequest {
            platform: "".into(),
            ..sample_create_request()
        };
        assert!(validate_create_request(&req).is_err());
    }

    #[test]
    fn validate_create_missing_name() {
        let req = CreateProviderRequest {
            name: "  ".into(),
            ..sample_create_request()
        };
        assert!(validate_create_request(&req).is_err());
    }

    #[test]
    fn validate_create_missing_base_url() {
        let req = CreateProviderRequest {
            base_url: "".into(),
            ..sample_create_request()
        };
        assert!(validate_create_request(&req).is_err());
    }

    #[test]
    fn validate_create_invalid_url() {
        let req = CreateProviderRequest {
            base_url: "not-a-url".into(),
            ..sample_create_request()
        };
        assert!(validate_create_request(&req).is_err());
    }

    #[test]
    fn validate_create_missing_api_key() {
        let req = CreateProviderRequest {
            api_key: "  ".into(),
            ..sample_create_request()
        };
        assert!(validate_create_request(&req).is_err());
    }

    #[test]
    fn validate_create_valid() {
        assert!(validate_create_request(&sample_create_request()).is_ok());
    }

    #[test]
    fn validate_create_bedrock_allows_empty_base_url_and_api_key() {
        let req = CreateProviderRequest {
            platform: "bedrock".into(),
            name: "AWS Bedrock".into(),
            base_url: "".into(),
            api_key: "".into(),
            bedrock_config: Some(nomifun_api_types::BedrockConfig {
                auth_method: nomifun_api_types::BedrockAuthMethod::Profile,
                region: "us-west-2".into(),
                profile: Some("ai".into()),
                access_key_id: None,
                secret_access_key: None,
            }),
            ..sample_create_request()
        };
        assert!(validate_create_request(&req).is_ok());
    }

    #[test]
    fn validate_create_bedrock_requires_bedrock_config() {
        let req = CreateProviderRequest {
            platform: "bedrock".into(),
            name: "AWS Bedrock".into(),
            base_url: "".into(),
            api_key: "".into(),
            bedrock_config: None,
            ..sample_create_request()
        };
        assert!(validate_create_request(&req).is_err());
    }

    #[test]
    fn validate_update_empty_name_rejected() {
        let req = UpdateProviderRequest {
            name: Some("".into()),
            ..Default::default()
        };
        assert!(validate_update_request(&req).is_err());
    }

    #[test]
    fn validate_update_empty_request_ok() {
        assert!(validate_update_request(&UpdateProviderRequest::default()).is_ok());
    }

    #[test]
    fn validate_update_empty_base_url_ok() {
        let req = UpdateProviderRequest {
            base_url: Some("".into()),
            ..Default::default()
        };
        assert!(validate_update_request(&req).is_ok());
    }

    #[test]
    fn validate_update_invalid_base_url_rejected() {
        let req = UpdateProviderRequest {
            base_url: Some("not-a-url".into()),
            ..Default::default()
        };
        assert!(validate_update_request(&req).is_err());
    }

    #[test]
    fn validate_base_url_http() {
        assert!(validate_base_url("http://localhost:8080").is_ok());
    }

    #[test]
    fn validate_base_url_https() {
        assert!(validate_base_url("https://api.example.com").is_ok());
    }

    #[test]
    fn validate_base_url_ftp_rejected() {
        assert!(validate_base_url("ftp://files.example.com").is_err());
    }

    // -- service integration tests --

    #[tokio::test]
    async fn list_empty() {
        let svc = setup().await;
        let result = svc.list().await.unwrap();
        assert!(result.is_empty());
    }

    #[tokio::test]
    async fn create_and_list() {
        let svc = setup().await;
        let created = svc.create(sample_create_request()).await.unwrap();

        assert!(created.id.starts_with("prov_"));
        assert_eq!(created.platform, "anthropic");
        assert_eq!(created.name, "Anthropic");
        assert_eq!(created.base_url, "https://api.anthropic.com");
        // API key is returned in plaintext (pre-launch; encrypted at rest).
        assert_eq!(created.api_key, "sk-ant-api03-test1234");
        assert_eq!(created.models, vec!["claude-sonnet-4-20250514"]);
        assert!(created.enabled);

        let all = svc.list().await.unwrap();
        assert_eq!(all.len(), 1);
        assert_eq!(all[0].id, created.id);
        assert_eq!(all[0].api_key, "sk-ant-api03-test1234");
    }

    #[tokio::test]
    async fn create_with_provided_id() {
        let svc = setup().await;
        let req = CreateProviderRequest {
            id: Some("caller-id-xyz".into()),
            ..sample_create_request()
        };
        let created = svc.create(req).await.unwrap();
        assert_eq!(created.id, "caller-id-xyz");
    }

    #[tokio::test]
    async fn create_with_provided_id_rejects_invalid() {
        let svc = setup().await;
        let req = CreateProviderRequest {
            id: Some("   ".into()),
            ..sample_create_request()
        };
        let err = svc.create(req).await.unwrap_err();
        assert_eq!(err.status_code(), axum::http::StatusCode::BAD_REQUEST);
    }

    #[tokio::test]
    async fn create_with_duplicate_id_returns_conflict() {
        let svc = setup().await;
        let req1 = CreateProviderRequest {
            id: Some("dup-id".into()),
            ..sample_create_request()
        };
        svc.create(req1).await.unwrap();

        let req2 = CreateProviderRequest {
            id: Some("dup-id".into()),
            ..sample_create_request()
        };
        let err = svc.create(req2).await.unwrap_err();
        assert_eq!(err.status_code(), axum::http::StatusCode::CONFLICT);
    }

    #[tokio::test]
    async fn create_persists_per_model_fields() {
        use std::collections::HashMap;
        let svc = setup().await;
        let req = CreateProviderRequest {
            model_protocols: Some(HashMap::from([("gpt-4".into(), "openai".into())])),
            model_enabled: Some(HashMap::from([("gpt-4".into(), true), ("gpt-3.5".into(), false)])),
            ..sample_create_request()
        };
        let created = svc.create(req).await.unwrap();

        assert_eq!(
            created.model_protocols.as_ref().and_then(|m| m.get("gpt-4")),
            Some(&"openai".to_string())
        );
        assert_eq!(created.model_enabled.as_ref().and_then(|m| m.get("gpt-4")), Some(&true));
        assert_eq!(
            created.model_enabled.as_ref().and_then(|m| m.get("gpt-3.5")),
            Some(&false)
        );

        // And persist through a fresh read.
        let all = svc.list().await.unwrap();
        assert_eq!(all[0].model_enabled.as_ref().and_then(|m| m.get("gpt-4")), Some(&true));
    }

    #[tokio::test]
    async fn provider_response_api_key_plaintext_matches_input() {
        // Replaces the masking test: api_key on the response is the
        // encrypted-then-decrypted plaintext (equal to the input).
        let svc = setup().await;
        let req = CreateProviderRequest {
            api_key: "sk-secret-original-value".into(),
            ..sample_create_request()
        };
        let created = svc.create(req).await.unwrap();
        assert_eq!(created.api_key, "sk-secret-original-value");
        assert!(!created.api_key.contains("***"));
    }

    #[tokio::test]
    async fn create_invalid_request_rejected() {
        let svc = setup().await;
        let req = CreateProviderRequest {
            platform: "".into(),
            ..sample_create_request()
        };
        let err = svc.create(req).await.unwrap_err();
        assert_eq!(err.status_code(), axum::http::StatusCode::BAD_REQUEST);
    }

    #[tokio::test]
    async fn update_name() {
        let svc = setup().await;
        let created = svc.create(sample_create_request()).await.unwrap();

        let updated = svc
            .update(
                &created.id,
                UpdateProviderRequest {
                    name: Some("New Name".into()),
                    ..Default::default()
                },
            )
            .await
            .unwrap();

        assert_eq!(updated.name, "New Name");
        assert_eq!(updated.platform, "anthropic");
    }

    #[tokio::test]
    async fn update_api_key_re_encrypts() {
        let svc = setup().await;
        let created = svc.create(sample_create_request()).await.unwrap();

        let updated = svc
            .update(
                &created.id,
                UpdateProviderRequest {
                    api_key: Some("new-key-abcdefgh".into()),
                    ..Default::default()
                },
            )
            .await
            .unwrap();

        // Response carries the new plaintext key (encrypted at rest).
        assert_eq!(updated.api_key, "new-key-abcdefgh");
    }

    #[tokio::test]
    async fn update_nonexistent_returns_not_found() {
        let svc = setup().await;
        let err = svc
            .update("no_such_id", UpdateProviderRequest::default())
            .await
            .unwrap_err();
        assert_eq!(err.status_code(), axum::http::StatusCode::NOT_FOUND);
    }

    #[tokio::test]
    async fn delete_existing() {
        let svc = setup().await;
        let created = svc.create(sample_create_request()).await.unwrap();

        svc.delete(&created.id).await.unwrap();
        let all = svc.list().await.unwrap();
        assert!(all.is_empty());
    }

    #[tokio::test]
    async fn delete_nonexistent_returns_not_found() {
        let svc = setup().await;
        let err = svc.delete("no_such_id").await.unwrap_err();
        assert_eq!(err.status_code(), axum::http::StatusCode::NOT_FOUND);
    }
}