use std::fmt;

use actix_web::http::StatusCode;
use api::rest::{AppResponseData, NoData};
use utoipa::IntoResponses;

use crate::share::errors::GitError;

#[derive(Debug)]
pub enum GitApiError {
    BadRequest(String),
    Unauthorized,
    Forbidden,
    NotFound,
    Conflict(String),
    Internal(String),
}

impl fmt::Display for GitApiError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            Self::BadRequest(message) => write!(f, "{message}"),
            Self::Unauthorized => write!(f, "unauthorized"),
            Self::Forbidden => write!(f, "forbidden"),
            Self::NotFound => write!(f, "not found"),
            Self::Conflict(message) => write!(f, "{message}"),
            Self::Internal(message) => write!(f, "{message}"),
        }
    }
}

impl std::error::Error for GitApiError {}

impl From<GitError> for GitApiError {
    fn from(error: GitError) -> Self {
        match error {
            GitError::NotFound => Self::NotFound,
            GitError::Unauthorized => Self::Unauthorized,
            GitError::Forbidden => Self::Forbidden,
            GitError::Conflict(msg) => Self::Conflict(msg),
            GitError::InvalidArgument(msg) => Self::BadRequest(msg),
            GitError::Unimplemented(msg) => Self::Internal(msg.to_string()),
            GitError::Cache(_) | GitError::Git(_) | GitError::Internal(_) => {
                tracing::warn!(error = %error, "git handler failed");
                Self::Internal("internal server error".to_string())
            }
        }
    }
}

impl From<dir::Error> for GitError {
    fn from(error: dir::Error) -> Self {
        match error {
            dir::Error::InvalidInput(message) => Self::InvalidArgument(message),
            dir::Error::NotFound => Self::NotFound,
            dir::Error::Database(error) => Self::from(error),
        }
    }
}

impl From<sea_orm::DbErr> for GitApiError {
    fn from(error: sea_orm::DbErr) -> Self {
        if is_unique_violation(&error) {
            return Self::Conflict("resource already exists".to_string());
        }
        Self::Internal(format!("database error: {error}"))
    }
}

impl From<serde_json::Error> for GitApiError {
    fn from(error: serde_json::Error) -> Self {
        Self::BadRequest(format!("invalid payload: {error}"))
    }
}

fn is_unique_violation(err: &sea_orm::DbErr) -> bool {
    let msg = err.to_string().to_lowercase();
    msg.contains("unique") || msg.contains("duplicate") || msg.contains("23505")
}

#[derive(Debug, IntoResponses)]
pub enum ApiError {
    #[response(status = 400, description = "request failed validation")]
    BadRequest(#[to_schema] Box<AppResponseData<NoData>>),
    #[response(status = 401, description = "authentication required")]
    Unauthorized(#[to_schema] Box<AppResponseData<NoData>>),
    #[response(status = 403, description = "operation not allowed")]
    Forbidden(#[to_schema] Box<AppResponseData<NoData>>),
    #[response(status = 404, description = "resource not found")]
    NotFound(#[to_schema] Box<AppResponseData<NoData>>),
    #[response(status = 409, description = "resource conflict")]
    Conflict(#[to_schema] Box<AppResponseData<NoData>>),
    #[response(status = 500, description = "internal server error")]
    Internal(#[to_schema] Box<AppResponseData<NoData>>),
}

impl ApiError {
    /// Boxes a plain envelope into the enum's payload. The box keeps
    /// `Result<T, ApiError>` small: an inline envelope is 128 bytes, which every
    /// handler return type would otherwise carry on the happy path too.
    fn payload(code: i32, message: &'static str) -> Box<AppResponseData<NoData>> {
        Box::new(AppResponseData::err(code, message))
    }
}

impl ApiError {
    pub fn bad_request() -> Self {
        Self::BadRequest(Self::payload(400, "bad request"))
    }

    pub fn unauthorized() -> Self {
        Self::Unauthorized(Self::payload(401, "unauthorized"))
    }

    pub fn forbidden() -> Self {
        Self::Forbidden(Self::payload(403, "forbidden"))
    }

    pub fn not_found() -> Self {
        Self::NotFound(Self::payload(404, "not found"))
    }

    pub fn conflict(message: impl Into<String>) -> Self {
        Self::Conflict(Box::new(AppResponseData::err(409, message)))
    }

    pub fn internal() -> Self {
        Self::Internal(Self::payload(500, "internal server error"))
    }
}

impl std::fmt::Display for ApiError {
    fn fmt(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        let (_, envelope) = self.parts();
        formatter.write_str(&envelope.message)
    }
}

impl ApiError {
    fn parts(&self) -> (u16, &AppResponseData<NoData>) {
        match self {
            Self::BadRequest(envelope) => (400, envelope),
            Self::Unauthorized(envelope) => (401, envelope),
            Self::Forbidden(envelope) => (403, envelope),
            Self::NotFound(envelope) => (404, envelope),
            Self::Conflict(envelope) => (409, envelope),
            Self::Internal(envelope) => (500, envelope),
        }
    }
}

impl actix_web::ResponseError for ApiError {
    fn status_code(&self) -> StatusCode {
        StatusCode::from_u16(self.parts().0).unwrap_or(StatusCode::INTERNAL_SERVER_ERROR)
    }

    fn error_response(&self) -> actix_web::HttpResponse {
        let (status, envelope) = self.parts();
        let status = StatusCode::from_u16(status).unwrap_or(StatusCode::INTERNAL_SERVER_ERROR);
        actix_web::HttpResponse::build(status).json(envelope)
    }
}

impl From<GitApiError> for ApiError {
    fn from(error: GitApiError) -> Self {
        match error {
            GitApiError::BadRequest(msg) => {
                Self::BadRequest(Box::new(AppResponseData::err(400, msg)))
            }
            GitApiError::Unauthorized => Self::Unauthorized(Self::payload(401, "unauthorized")),
            GitApiError::Forbidden => Self::Forbidden(Self::payload(403, "forbidden")),
            GitApiError::NotFound => Self::NotFound(Self::payload(404, "not found")),
            GitApiError::Conflict(msg) => Self::Conflict(Box::new(AppResponseData::err(409, msg))),
            GitApiError::Internal(message) => {
                tracing::warn!(error = %message, "git handler failed");
                Self::Internal(Self::payload(500, "internal server error"))
            }
        }
    }
}