use crate::{
    amount::AmountCents, asset::AssetId, storage::Error, AccountId, Amount, Asset, AssetManager,
    Payment, PaymentId, Status, Storage, Transaction, TransactionId,
};
use futures::TryStreamExt;
use sqlx::{sqlite::SqliteRow, Executor, Row};
use std::{collections::HashMap, marker::PhantomData};

mod batch;

pub use batch::Batch;

pub struct Sqlite<'a> {
    db: sqlx::SqlitePool,
    asset_manager: AssetManager,
    _phantom: PhantomData<&'a ()>,
}

impl<'a> Sqlite<'a> {
    pub fn new(db: sqlx::SqlitePool, asset_manager: AssetManager) -> Self {
        Self {
            db,
            asset_manager,
            _phantom: PhantomData,
        }
    }

    pub async fn setup(&self) -> Result<(), sqlx::Error> {
        let mut x = self.db.begin().await?;
        x.execute(
            r#"CREATE TABLE IF NOT EXISTS "payments" (
                "transaction_id" VARCHAR(66) NOT NULL,
                "position_id" INTEGER NOT NULL,
                "asset_id" TEXT NOT NULL,
                "cents" TEXT NOT NULL,
                "status" INTEGER NOT NULL,
                "to" VARCHAR(71) NOT NULL,
                "spent_by" TEXT,
                "created_at" DATETIME DEFAULT CURRENT_TIMESTAMP,
                "updated_at" DATETIME DEFAULT CURRENT_TIMESTAMP,
                PRIMARY KEY ("transaction_id", "position_id")
            );
            CREATE INDEX IF NOT EXISTS payments_to ON payments ("to", "asset_id", "status", "spent_by");
            CREATE TABLE IF NOT EXISTS "transactions" (
                "transaction_id" VARCHAR(66) NOT NULL,
                "status" INTEGER NOT NULL,
                "reference" TEXT NOT NULL,
                "created_at" DATETIME DEFAULT CURRENT_TIMESTAMP,
                "updated_at" DATETIME DEFAULT CURRENT_TIMESTAMP,
                PRIMARY KEY ("transaction_id")
            );
            CREATE TABLE IF NOT EXISTS "transaction_payments" (
                "transaction_id" VARCHAR(66) NOT NULL,
                "payment_transaction_id" VARCHAR(66) NOT NULL,
                "payment_position_id"  INTEGER NOT NULL,
                "created_at" DATETIME DEFAULT CURRENT_TIMESTAMP,
                "updated_at" DATETIME DEFAULT CURRENT_TIMESTAMP,
                PRIMARY KEY ("transaction_id", "payment_transaction_id", "payment_position_id")
            );
        "#,
        )
        .await
        .expect("valid");
        x.commit().await?;
        Ok(())
    }

    #[inline]
    fn sql_row_to_payment(&self, row: SqliteRow) -> Result<Payment, Error> {
        let id = PaymentId {
            transaction: row
                .try_get::<String, usize>(0)
                .map_err(|_| Error::Storage("Invalid payment_id".to_string()))?
                .as_str()
                .try_into()
                .map_err(|_| Error::Storage("Invalid transaction_id length".to_string()))?,
            position: row
                .try_get::<i64, usize>(1)
                .map_err(|_| Error::Storage("Invalid payment_id".to_string()))?
                .try_into()
                .map_err(|_| Error::Storage("Invalid payment_id".to_string()))?,
        };

        let cents = row
            .try_get::<String, usize>(3)
            .map_err(|_| Error::Storage("Invalid cents".to_string()))?
            .parse::<i128>()
            .map_err(|_| Error::Storage("Invalid cents".to_string()))?;

        Ok(Payment {
            id,
            amount: self
                .asset_manager
                .asset(
                    row.try_get::<String, usize>(2)
                        .map_err(|_| Error::Storage("Invalid asset_id".to_string()))?
                        .parse()
                        .map_err(|_| Error::Storage("Invalid asset_id".to_string()))?,
                )
                .map_err(|e| Error::Storage(e.to_string()))?
                .new_amount(cents),
            to: row
                .try_get::<String, usize>(4)
                .map_err(|_| Error::Storage("Invalid `to`".to_string()))?
                .as_str()
                .try_into()
                .map_err(|_| Error::Storage("Invalid `to`".to_string()))?,
            status: row
                .try_get::<u32, usize>(5)
                .map_err(|_| Error::Storage("Invalid `status`".to_string()))?
                .try_into()
                .map_err(|_| Error::Storage("Invalid status".to_string()))?,
            spent_by: row
                .try_get::<Option<String>, usize>(6)
                .map_err(|_| Error::Storage("Invalid spent_by".to_string()))?
                .map(|s| s.as_str().try_into())
                .transpose()
                .map_err(|_| Error::Storage("Invalid spent_by".to_string()))?,
        })
    }
}

#[async_trait::async_trait]
impl<'a> Storage<'a, Batch<'a>> for Sqlite<'a> {
    async fn begin(&'a self) -> Result<Batch<'a>, Error> {
        self.db
            .begin()
            .await
            .map(|x| Batch::new(x))
            .map_err(|x| Error::Storage(x.to_string()))
    }

    async fn get_payment(&self, id: PaymentId) -> Result<Payment, Error> {
        let mut conn = self
            .db
            .acquire()
            .await
            .map_err(|e| Error::Storage(e.to_string()))?;

        let row = sqlx::query(
            r#"
            SELECT
                "p"."transaction_id",
                "p"."position_id",
                "p"."asset_id",
                "p"."cents",
                "p"."to",
                "p"."status",
                "p"."spent_by"
            FROM
                "payments" "p"
            WHERE
                "p"."transaction_id" = ?
                AND "p"."position_id" = ?
            LIMIT 1
            "#,
        )
        .bind(id.transaction.to_string())
        .bind(id.position.to_string())
        .fetch_optional(&mut *conn)
        .await
        .map_err(|e| Error::Storage(e.to_string()))?
        .ok_or(Error::NotFound)?;

        self.sql_row_to_payment(row)
    }

    async fn get_balance(&self, account: &AccountId) -> Result<Vec<Amount>, Error> {
        let mut conn = self
            .db
            .acquire()
            .await
            .map_err(|e| Error::Storage(e.to_string()))?;

        let mut result = sqlx::query(
            r#"
            SELECT
                "asset_id",
                "cents"
            FROM
                "payments"
            WHERE
                "to" = ? AND status = ? AND "spent_by" IS NULL
            "#,
        )
        .bind(account.to_string())
        .bind::<u32>(Status::Settled.into())
        .fetch(&mut *conn);

        let mut balances = HashMap::<Asset, Amount>::new();

        while let Some(row) = result
            .try_next()
            .await
            .map_err(|e| Error::Storage(e.to_string()))?
        {
            let asset = self
                .asset_manager
                .asset(
                    row.try_get::<String, usize>(0)
                        .map_err(|_| Error::Storage("Invalid asset_id".to_string()))?
                        .parse()
                        .map_err(|_| Error::Storage("Invalid asset_id".to_string()))?,
                )
                .map_err(|e| Error::Storage(e.to_string()))?;

            let cents = row
                .try_get::<String, usize>(1)
                .map_err(|_| Error::Storage("Invalid cents".to_string()))?
                .parse::<i128>()
                .map_err(|_| Error::Storage("Invalid cents".to_string()))?;

            let new_amount = asset.new_amount(cents);

            if let Some(amount) = balances.get_mut(&asset) {
                *amount = amount
                    .checked_add(&new_amount)
                    .ok_or(Error::Storage("amount overflow".to_owned()))?;
            } else {
                balances.insert(asset, new_amount);
            }
        }

        Ok(balances.into_iter().map(|(_, v)| v).collect())
    }

    async fn get_unspent_payments(
        &self,
        account: &AccountId,
        asset: AssetId,
        mut target_amount: AmountCents,
    ) -> Result<Vec<Payment>, Error> {
        let mut conn = self
            .db
            .acquire()
            .await
            .map_err(|e| Error::Storage(e.to_string()))?;
        let mut result = sqlx::query(
            r#"
            SELECT
                "p"."transaction_id",
                "p"."position_id",
                "p"."asset_id",
                "p"."cents",
                "p"."to",
                "p"."status",
                "p"."spent_by"
            FROM
                "payments" as "p"
            WHERE
                "p"."to" = ? AND "p"."asset_id" = ? AND status = ? AND "p"."spent_by" IS NULL
            ORDER BY cents ASC
            "#,
        )
        .bind(account.to_string())
        .bind(asset.to_string())
        .bind::<u32>(Status::Settled.into())
        .fetch(&mut *conn);

        let mut to_return = vec![];
        while let Some(row) = result
            .try_next()
            .await
            .map_err(|e| Error::Storage(e.to_string()))?
        {
            let row = self.sql_row_to_payment(row)?;
            target_amount -= row.amount.cents();
            to_return.push(row);
            if target_amount <= 0 {
                break;
            }
        }

        if target_amount <= 0 {
            Ok(to_return)
        } else {
            Err(Error::NotEnoughUnspentPayments(target_amount))
        }
    }

    async fn get_transaction(&self, transaction_id: &TransactionId) -> Result<Transaction, Error> {
        let mut conn = self
            .db
            .acquire()
            .await
            .map_err(|e| Error::Storage(e.to_string()))?;

        let transaction_row = sqlx::query(
            r#"
            SELECT
                "t"."status",
                "t"."reference"
            FROM
                "transactions" "t"
            WHERE
                "t"."transaction_id" = ?
            "#,
        )
        .bind(transaction_id.to_string())
        .fetch_optional(&mut *conn)
        .await
        .map_err(|e| Error::Storage(e.to_string()))?
        .ok_or(Error::NotFound)?;

        let mut spend_result = sqlx::query(
            r#"
            SELECT
                "p"."transaction_id",
                "p"."position_id",
                "p"."asset_id",
                "p"."cents",
                "p"."to",
                "p"."status",
                "p"."spent_by"
            FROM
                "payments" "p"
            INNER JOIN 
                "transaction_payments" "tp" 
                ON (
                    "tp"."payment_transaction_id" = "p"."transaction_id" 
                    AND "tp"."payment_position_id" = "p"."position_id"
                )
            WHERE
                "tp"."transaction_id" = ?
            "#,
        )
        .bind(transaction_id.to_string())
        .fetch(&mut *conn);

        let mut spend = vec![];

        while let Some(row) = spend_result
            .try_next()
            .await
            .map_err(|e| Error::Storage(e.to_string()))?
        {
            spend.push(self.sql_row_to_payment(row)?);
        }

        drop(spend_result);

        let mut create_result = sqlx::query(
            r#"
            SELECT
                "p"."transaction_id",
                "p"."position_id",
                "p"."asset_id",
                "p"."cents",
                "p"."to",
                "p"."status",
                "p"."spent_by"
            FROM
                "payments" "p"
            WHERE
                "p"."transaction_id" = ?
            "#,
        )
        .bind(transaction_id.to_string())
        .fetch(&mut *conn);

        let mut create = vec![];

        while let Some(row) = create_result
            .try_next()
            .await
            .map_err(|e| Error::Storage(e.to_string()))?
        {
            create.push(self.sql_row_to_payment(row)?);
        }

        let status = transaction_row
            .try_get::<u32, usize>(0)
            .map_err(|_| Error::Storage("Invalid status".to_string()))?
            .try_into()
            .map_err(|_| Error::Storage("Invalid status".to_string()))?;
        let reference = transaction_row
            .try_get::<String, usize>(1)
            .map_err(|_| Error::Storage("Invalid reference".to_string()))?;

        Ok(Transaction {
            id: transaction_id.clone(),
            is_external_deposit: spend.is_empty(),
            spend,
            create,
            status,
            reference,
        })
    }
}