#[cfg(feature = "serde")]
use serde::{Deserialize, Serialize};
use std::str::{self, FromStr};
use std::{env, fmt};

use crate::error::RegionError;

/// AWS S3 [region identifier](https://docs.aws.amazon.com/general/latest/gr/rande.html#s3_region),
/// passing in custom values is also possible, in that case it is up to you to pass a valid endpoint,
/// otherwise boom will happen :)
///
/// Serde support available with the `serde` feature
///
/// # Example
/// ```
/// use std::str::FromStr;
/// use awsregion::Region;
///
/// // Parse from a string
/// let region: Region = "us-east-1".parse().unwrap();
///
/// // Choose region directly
/// let region = Region::EuWest2;
///
/// // Custom region requires valid region name and endpoint
/// let region_name = "nl-ams".to_string();
/// let endpoint = "https://s3.nl-ams.scw.cloud".to_string();
/// let region = Region::Custom { region: region_name, endpoint };
///
/// ```
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
#[derive(Clone, Debug, Eq, PartialEq)]
pub enum Region {
    /// us-east-1
    UsEast1,
    /// us-east-2
    UsEast2,
    /// us-west-1
    UsWest1,
    /// us-west-2
    UsWest2,
    /// ca-central-1
    CaCentral1,
    /// af-south-1
    AfSouth1,
    /// ap-east-1
    ApEast1,
    /// ap-south-1
    ApSouth1,
    /// ap-northeast-1
    ApNortheast1,
    /// ap-northeast-2
    ApNortheast2,
    /// ap-northeast-3
    ApNortheast3,
    /// ap-southeast-1
    ApSoutheast1,
    /// ap-southeast-2
    ApSoutheast2,
    /// cn-north-1
    CnNorth1,
    /// cn-northwest-1
    CnNorthwest1,
    /// eu-north-1
    EuNorth1,
    /// eu-central-1
    EuCentral1,
    /// eu-central-2
    EuCentral2,
    /// eu-west-1
    EuWest1,
    /// eu-west-2
    EuWest2,
    /// eu-west-3
    EuWest3,
    /// il-central-1
    IlCentral1,
    /// me-south-1
    MeSouth1,
    /// sa-east-1
    SaEast1,
    /// Digital Ocean nyc3
    DoNyc3,
    /// Digital Ocean ams3
    DoAms3,
    /// Digital Ocean sgp1
    DoSgp1,
    /// Digital Ocean fra1
    DoFra1,
    /// Yandex Object Storage
    Yandex,
    /// Wasabi us-east-1
    WaUsEast1,
    /// Wasabi us-east-2
    WaUsEast2,
    /// Wasabi us-west-1
    WaUsWest1,
    /// Wasabi eu-central-1
    WaEuCentral1,
    /// Custom region
    R2 {
        account_id: String,
    },
    Custom {
        region: String,
        endpoint: String,
    },
}

impl fmt::Display for Region {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        use self::Region::*;
        match *self {
            UsEast1 => write!(f, "us-east-1"),
            UsEast2 => write!(f, "us-east-2"),
            UsWest1 => write!(f, "us-west-1"),
            UsWest2 => write!(f, "us-west-2"),
            AfSouth1 => write!(f, "af-south-1"),
            CaCentral1 => write!(f, "ca-central-1"),
            ApEast1 => write!(f, "ap-east-1"),
            ApSouth1 => write!(f, "ap-south-1"),
            ApNortheast1 => write!(f, "ap-northeast-1"),
            ApNortheast2 => write!(f, "ap-northeast-2"),
            ApNortheast3 => write!(f, "ap-northeast-3"),
            ApSoutheast1 => write!(f, "ap-southeast-1"),
            ApSoutheast2 => write!(f, "ap-southeast-2"),
            CnNorth1 => write!(f, "cn-north-1"),
            CnNorthwest1 => write!(f, "cn-northwest-1"),
            EuNorth1 => write!(f, "eu-north-1"),
            EuCentral1 => write!(f, "eu-central-1"),
            EuCentral2 => write!(f, "eu-central-2"),
            EuWest1 => write!(f, "eu-west-1"),
            EuWest2 => write!(f, "eu-west-2"),
            EuWest3 => write!(f, "eu-west-3"),
            SaEast1 => write!(f, "sa-east-1"),
            IlCentral1 => write!(f, "il-central-1"),
            MeSouth1 => write!(f, "me-south-1"),
            DoNyc3 => write!(f, "nyc3"),
            DoAms3 => write!(f, "ams3"),
            DoSgp1 => write!(f, "sgp1"),
            DoFra1 => write!(f, "fra1"),
            Yandex => write!(f, "ru-central1"),
            WaUsEast1 => write!(f, "us-east-1"),
            WaUsEast2 => write!(f, "us-east-2"),
            WaUsWest1 => write!(f, "us-west-1"),
            WaEuCentral1 => write!(f, "eu-central-1"),
            R2 { .. } => write!(f, "auto"),
            Custom { ref region, .. } => write!(f, "{}", region),
        }
    }
}

impl FromStr for Region {
    type Err = std::str::Utf8Error;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        use self::Region::*;
        match s {
            "us-east-1" => Ok(UsEast1),
            "us-east-2" => Ok(UsEast2),
            "us-west-1" => Ok(UsWest1),
            "us-west-2" => Ok(UsWest2),
            "ca-central-1" => Ok(CaCentral1),
            "af-south-1" => Ok(AfSouth1),
            "ap-east-1" => Ok(ApEast1),
            "ap-south-1" => Ok(ApSouth1),
            "ap-northeast-1" => Ok(ApNortheast1),
            "ap-northeast-2" => Ok(ApNortheast2),
            "ap-northeast-3" => Ok(ApNortheast3),
            "ap-southeast-1" => Ok(ApSoutheast1),
            "ap-southeast-2" => Ok(ApSoutheast2),
            "cn-north-1" => Ok(CnNorth1),
            "cn-northwest-1" => Ok(CnNorthwest1),
            "eu-north-1" => Ok(EuNorth1),
            "eu-central-1" => Ok(EuCentral1),
            "eu-central-2" => Ok(EuCentral2),
            "eu-west-1" => Ok(EuWest1),
            "eu-west-2" => Ok(EuWest2),
            "eu-west-3" => Ok(EuWest3),
            "sa-east-1" => Ok(SaEast1),
            "il-central-1" => Ok(IlCentral1),
            "me-south-1" => Ok(MeSouth1),
            "nyc3" => Ok(DoNyc3),
            "ams3" => Ok(DoAms3),
            "sgp1" => Ok(DoSgp1),
            "fra1" => Ok(DoFra1),
            "yandex" => Ok(Yandex),
            "ru-central1" => Ok(Yandex),
            "wa-us-east-1" => Ok(WaUsEast1),
            "wa-us-east-2" => Ok(WaUsEast2),
            "wa-us-west-1" => Ok(WaUsWest1),
            "wa-eu-central-1" => Ok(WaEuCentral1),
            x => Ok(Custom {
                region: x.to_string(),
                endpoint: x.to_string(),
            }),
        }
    }
}

impl Region {
    pub fn endpoint(&self) -> String {
        use self::Region::*;
        match *self {
            // Surprisingly, us-east-1 does not have a
            // s3-us-east-1.amazonaws.com DNS record
            UsEast1 => String::from("s3.amazonaws.com"),
            UsEast2 => String::from("s3-us-east-2.amazonaws.com"),
            UsWest1 => String::from("s3-us-west-1.amazonaws.com"),
            UsWest2 => String::from("s3-us-west-2.amazonaws.com"),
            CaCentral1 => String::from("s3-ca-central-1.amazonaws.com"),
            AfSouth1 => String::from("s3-af-south-1.amazonaws.com"),
            ApEast1 => String::from("s3-ap-east-1.amazonaws.com"),
            ApSouth1 => String::from("s3-ap-south-1.amazonaws.com"),
            ApNortheast1 => String::from("s3-ap-northeast-1.amazonaws.com"),
            ApNortheast2 => String::from("s3-ap-northeast-2.amazonaws.com"),
            ApNortheast3 => String::from("s3-ap-northeast-3.amazonaws.com"),
            ApSoutheast1 => String::from("s3-ap-southeast-1.amazonaws.com"),
            ApSoutheast2 => String::from("s3-ap-southeast-2.amazonaws.com"),
            CnNorth1 => String::from("s3.cn-north-1.amazonaws.com.cn"),
            CnNorthwest1 => String::from("s3.cn-northwest-1.amazonaws.com.cn"),
            EuNorth1 => String::from("s3-eu-north-1.amazonaws.com"),
            EuCentral1 => String::from("s3.eu-central-1.amazonaws.com"),
            EuCentral2 => String::from("s3.eu-central-2.amazonaws.com"),
            EuWest1 => String::from("s3-eu-west-1.amazonaws.com"),
            EuWest2 => String::from("s3-eu-west-2.amazonaws.com"),
            EuWest3 => String::from("s3-eu-west-3.amazonaws.com"),
            SaEast1 => String::from("s3-sa-east-1.amazonaws.com"),
            IlCentral1 => String::from("s3.il-central-1.amazonaws.com"),
            MeSouth1 => String::from("s3-me-south-1.amazonaws.com"),
            DoNyc3 => String::from("nyc3.digitaloceanspaces.com"),
            DoAms3 => String::from("ams3.digitaloceanspaces.com"),
            DoSgp1 => String::from("sgp1.digitaloceanspaces.com"),
            DoFra1 => String::from("fra1.digitaloceanspaces.com"),
            Yandex => String::from("storage.yandexcloud.net"),
            WaUsEast1 => String::from("s3.us-east-1.wasabisys.com"),
            WaUsEast2 => String::from("s3.us-east-2.wasabisys.com"),
            WaUsWest1 => String::from("s3.us-west-1.wasabisys.com"),
            WaEuCentral1 => String::from("s3.eu-central-1.wasabisys.com"),
            R2 { ref account_id } => format!("{}.r2.cloudflarestorage.com", account_id),
            Custom { ref endpoint, .. } => endpoint.to_string(),
        }
    }

    pub fn scheme(&self) -> String {
        match *self {
            Region::Custom { ref endpoint, .. } => match endpoint.find("://") {
                Some(pos) => endpoint[..pos].to_string(),
                None => "https".to_string(),
            },
            _ => "https".to_string(),
        }
    }

    pub fn host(&self) -> String {
        match *self {
            Region::Custom { ref endpoint, .. } => match endpoint.find("://") {
                Some(pos) => endpoint[pos + 3..].to_string(),
                None => endpoint.to_string(),
            },
            _ => self.endpoint(),
        }
    }

    pub fn from_env(region_env: &str, endpoint_env: Option<&str>) -> Result<Region, RegionError> {
        if let Some(endpoint_env) = endpoint_env {
            Ok(Region::Custom {
                region: env::var(region_env)?,
                endpoint: env::var(endpoint_env)?,
            })
        } else {
            Ok(Region::from_str(&env::var(region_env)?)?)
        }
    }

    /// Attempts to create a Region from AWS_REGION and AWS_ENDPOINT environment variables
    pub fn from_default_env() -> Result<Region, RegionError> {
        if let Ok(endpoint) = env::var("AWS_ENDPOINT") {
            Ok(Region::Custom {
                region: env::var("AWS_REGION")?,
                endpoint,
            })
        } else {
            Ok(Region::from_str(&env::var("AWS_REGION")?)?)
        }
    }
}

#[test]
fn yandex_object_storage() {
    let yandex = Region::Custom {
        endpoint: "storage.yandexcloud.net".to_string(),
        region: "ru-central1".to_string(),
    };

    let yandex_region = "ru-central1".parse::<Region>().unwrap();

    assert_eq!(yandex.endpoint(), yandex_region.endpoint());

    assert_eq!(yandex.to_string(), yandex_region.to_string());
}

#[test]
fn test_region_eu_central_2() {
    let region = "eu-central-2".parse::<Region>().unwrap();
    assert_eq!(region.endpoint(), "s3.eu-central-2.amazonaws.com");
}