use std::str::FromStr;
use std::sync::Arc;

use actix::{Addr, Message};
use chrono::prelude::*;

use crate::database::{Database, TokenByJti};
use crate::model::{AccountId, Audience, Token, TokenString};
use crate::{database, token_async_handler, Role};

struct Jwt {
    /// cti (customer id): Customer uuid identifier used by payment service
    pub cti: uuid::Uuid,
    /// arl (account role): account role
    pub arl: Role,
    /// iss (issuer): Issuer of the JWT
    pub iss: String,
    /// sub (subject): Subject of the JWT (the user)
    pub sub: i32,
    /// aud (audience): Recipient for which the JWT is intended
    pub aud: Audience,
    /// exp (expiration time): Time after which the JWT expires
    pub exp: chrono::NaiveDateTime,
    /// nbt (not before time): Time before which the JWT must not be accepted
    /// for processing
    pub nbt: chrono::NaiveDateTime,
    /// iat (issued at time): Time at which the JWT was issued; can be used to
    /// determine age of the JWT,
    pub iat: chrono::NaiveDateTime,
    /// jti (JWT ID): Unique identifier; can be used to prevent the JWT from
    /// being replayed (allows a token to be used only once)
    pub jti: uuid::Uuid,
}

#[derive(Debug, thiserror::Error)]
pub enum Error {
    #[error("Unable to save new token")]
    Save,
    #[error("Unable to save new token. Can't connect to database")]
    SaveInternal,
    #[error("Unable to validate token")]
    Validate,
    #[error("Unable to validate token. Can't connect to database")]
    ValidateInternal,
}

pub type Result<T> = std::result::Result<T, Error>;

pub struct TokenManager {
    db: Addr<Database>,
    secret: Arc<String>,
}

impl actix::Actor for TokenManager {
    type Context = actix::Context<Self>;
}

impl TokenManager {
    pub fn new(db: Addr<Database>) -> Self {
        let secret = Arc::new(std::env::var("JWT_SECRET").expect("JWT_SECRET is required"));
        Self { db, secret }
    }
}

#[derive(Message)]
#[rtype(result = "Result<(Token, TokenString)>")]
pub struct CreateToken {
    pub customer_id: uuid::Uuid,
    pub role: Role,
    pub subject: AccountId,
    pub audience: Option<Audience>,
}

token_async_handler!(CreateToken, create_token, (Token, TokenString));

async fn create_token(
    msg: CreateToken,
    db: Addr<Database>,
    secret: Arc<String>,
) -> Result<(Token, TokenString)> {
    let CreateToken {
        customer_id,
        role,
        subject,
        audience,
    } = msg;
    let audience = audience.unwrap_or_default();

    let token: Token = match db
        .send(database::CreateToken {
            customer_id,
            role,
            subject,
            audience,
        })
        .await
    {
        Ok(Ok(token)) => token,
        Ok(Err(db_err)) => {
            log::error!("{db_err}");
            return Err(Error::Save);
        }
        Err(act_err) => {
            log::error!("{act_err:?}");
            return Err(Error::SaveInternal);
        }
    };

    let token_string = {
        use std::collections::BTreeMap;

        use hmac::{Hmac, Mac};
        use jwt::SignWithKey;
        use sha2::Sha256;

        let key: Hmac<Sha256> = match Hmac::new_from_slice(secret.as_bytes()) {
            Ok(key) => key,
            Err(e) => {
                log::error!("{e:?}");
                return Err(Error::SaveInternal);
            }
        };
        let mut claims = BTreeMap::new();

        // cti (customer id): Customer uuid identifier used by payment service
        claims.insert("cti", format!("{}", token.customer_id));
        // arl (account role): account role
        claims.insert("arl", format!("{}", token.role.as_str()));
        // iss (issuer): Issuer of the JWT
        claims.insert("iss", format!("{}", token.issuer));
        // sub (subject): Subject of the JWT (the user)
        claims.insert("sub", format!("{}", token.subject));
        // aud (audience): Recipient for which the JWT is intended
        claims.insert("aud", format!("{}", token.audience.as_str()));
        // exp (expiration time): Time after which the JWT expires
        claims.insert("exp", format!("{}", token.expiration_time.format("%+")));
        // nbt (not before time): Time before which the JWT must not be accepted
        // for processing
        claims.insert("nbt", format!("{}", token.not_before_time.format("%+")));
        // iat (issued at time): Time at which the JWT was issued; can be used
        // to determine age of the JWT,
        claims.insert("iat", format!("{}", token.issued_at_time.format("%+")));
        // jti (JWT ID): Unique identifier; can be used to prevent the JWT from
        // being replayed (allows a token to be used only once)
        claims.insert("jti", format!("{}", token.jwt_id));

        TokenString::from(match claims.sign_with_key(&key) {
            Ok(s) => s,
            Err(e) => {
                log::error!("{e:?}");
                return Err(Error::SaveInternal);
            }
        })
    };
    Ok((token, token_string))
}

#[derive(Message)]
#[rtype(result = "Result<(Token, bool)>")]
pub struct Validate {
    pub token: TokenString,
}

token_async_handler!(Validate, validate, (Token, bool));

pub(crate) async fn validate(
    msg: Validate,
    db: Addr<Database>,
    secret: Arc<String>,
) -> Result<(Token, bool)> {
    use std::collections::BTreeMap;

    use hmac::{Hmac, Mac};
    use jwt::VerifyWithKey;
    use sha2::Sha256;

    log::info!("Validating token {:?}", msg.token);

    let key: Hmac<Sha256> = match Hmac::new_from_slice(secret.as_bytes()) {
        Ok(key) => key,
        Err(e) => {
            log::error!("{e:?}");
            return Err(Error::ValidateInternal);
        }
    };
    let claims: BTreeMap<String, String> = match msg.token.verify_with_key(&key) {
        Ok(claims) => claims,
        _ => return Err(Error::Validate),
    };
    let jti = match claims.get("jti") {
        Some(jti) => jti,
        _ => return Err(Error::Validate),
    };

    let token: Token = match db
        .send(TokenByJti {
            jti: String::from(jti),
        })
        .await
    {
        Ok(Ok(token)) => token,
        Ok(Err(e)) => {
            log::error!("{e}");
            return Err(Error::Validate);
        }
        Err(e) => {
            log::error!("{e:?}");
            return Err(Error::ValidateInternal);
        }
    };

    match (claims.get("cti"), &token.customer_id) {
        (Some(cti), id) => {
            if !uuid::Uuid::from_str(cti)
                .map(|u| u == *id)
                .unwrap_or_default()
            {
                return Ok((token, false));
            }
        }
        _ => return Ok((token, false)),
    }
    match (claims.get("arl"), &token.role) {
        (Some(arl), role) if arl == role.as_str() => {}
        _ => return Ok((token, false)),
    }
    match (claims.get("iss"), &token.issuer) {
        (Some(iss), issuer) if iss == issuer => {}
        _ => return Ok((token, false)),
    }
    match (claims.get("sub"), &token.subject) {
        (Some(sub), subject) => {
            if !sub
                .parse::<i32>()
                .map(|n| n == *subject)
                .unwrap_or_default()
            {
                return Ok((token, false));
            }
        }
        _ => return Ok((token, false)),
    }
    match (claims.get("aud"), &token.audience) {
        (Some(aud), audience) if aud == audience.as_str() => {}
        _ => return Ok((token, false)),
    }
    match (claims.get("exp"), &token.expiration_time) {
        (Some(left), right) if validate_time(left, right) => {}
        _ => return Ok((token, false)),
    }
    match (claims.get("nbt"), &token.not_before_time) {
        (Some(left), right) if validate_time(left, right) => {}
        _ => return Ok((token, false)),
    }
    match (claims.get("iat"), &token.issued_at_time) {
        (Some(left), right) if validate_time(left, right) => {}
        _ => return Ok((token, false)),
    }

    Ok((token, true))
}

fn validate_time(left: &str, right: &NaiveDateTime) -> bool {
    chrono::DateTime::parse_from_str(left, "%+")
        .map(|t| t.naive_utc() == *right)
        .unwrap_or_default()
}