use std::collections::HashMap;

use serde::{Deserialize, Serialize};
use serde_json::json;

use crate::{get_pg, transaction::Transaction};

pub fn timestamp_range(year: i32, month: u32) -> (i64, i64) {
    let d = chrono::NaiveDate::from_ymd_opt(year, month, 0).unwrap();
    let t = chrono::NaiveTime::from_hms_milli_opt(0, 0, 0, 0).unwrap();
    let start = chrono::NaiveDateTime::new(d, t).and_utc().timestamp();

    assert!(month <= 12);

    let end = if month == 12 {
        let d = chrono::NaiveDate::from_ymd_opt(year + 1, month, 0).unwrap();
        let t = chrono::NaiveTime::from_hms_milli_opt(0, 0, 0, 0).unwrap();
        chrono::NaiveDateTime::new(d, t).and_utc().timestamp()
    } else {
        let d = chrono::NaiveDate::from_ymd_opt(year, month + 1, 0).unwrap();
        let t = chrono::NaiveTime::from_hms_milli_opt(0, 0, 0, 0).unwrap();
        chrono::NaiveDateTime::new(d, t).and_utc().timestamp()
    };

    (start, end)
}

/// Represents a specific instance of an item with potential variations.
///
/// This struct is used to describe a particular variation or instance of an item
/// in the real world. It may include attributes or properties that deviate from
/// the standard definition of the item. For example, different colors, sizes, or
/// configurations.
#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
pub struct Variant {
    /// Associated Item
    pub item: String,
    /// Variant ID
    pub variant: String,
    /// Variant Name
    pub name: String,
    /// Minimum amount
    pub min: Option<i64>,
    /// Days until expiry
    pub expiry: Option<i64>,
    /// Associated barcodes
    pub barcodes: Option<Vec<i64>>
}

impl Variant {
    /// Create variant from itemdb yaml
    pub fn from_yml(json: &serde_yaml::Value, variant: &str, item: &str) -> Self {
        Self {
            item: item.to_string(),
            variant: variant.to_string(),
            name: json
                .as_mapping()
                .unwrap()
                .get("name")
                .unwrap()
                .as_str()
                .unwrap()
                .to_string(),
            min: json
                .as_mapping()
                .unwrap()
                .get("min")
                .map(|x| x.as_i64().unwrap()),
            expiry: json
                .as_mapping()
                .unwrap()
                .get("expiry")
                .map(|x| x.as_i64().unwrap()),
            barcodes: json.as_mapping().unwrap().get("barcodes").map(|x| {
                x.as_sequence().unwrap().into_iter().map(|x| x.as_i64().unwrap()).collect()
            })
        }
    }

    pub fn item_variant_id(&self) -> String {
        format!("{}::{}", self.item, self.variant)
    }

    /// Returns the IDs of Transactions from this Item Variant.
    pub async fn supply_log(&self) -> Vec<String> {
        let res: Vec<(uuid::Uuid,)> = sqlx::query_as(
            "SELECT id FROM transactions WHERE item = $1 AND variant = $2 ORDER BY created DESC",
        )
        .bind(&self.item)
        .bind(&self.variant)
        .fetch_all(get_pg!())
        .await
        .unwrap();

        res.into_iter().map(|x| x.0.to_string()).collect()
    }

    /// Returns the active Transaction of this Item Variant which are not yet consumed.
    pub async fn inventory(&self) -> Vec<Transaction> {
        sqlx::query_as("SELECT * FROM transactions WHERE item = $1 AND variant = $2 AND consumed_timestamp IS NULL ORDER BY created DESC")
        .bind(&self.item)
        .bind(&self.variant)
        .fetch_all(get_pg!()).await.unwrap()
    }

    /// Returns the IDs of the Transactions from this Item Variant which are consumed.
    pub async fn demand_log(&self, destination: Option<&str>) -> Vec<String> {
        let res: Vec<(uuid::Uuid,)> = if let Some(destination) = destination {
            sqlx::query_as(
                "SELECT id FROM transactions WHERE item = $1 AND variant = $2 AND consumed_timestamp IS NOT NULL AND destination = $3 ORDER BY created DESC"
            )
            .bind(&self.item)
            .bind(&self.variant)
            .bind(destination)
            .fetch_all(get_pg!()).await.unwrap()
        } else {
            sqlx::query_as(
            "SELECT id FROM transactions WHERE item = $1 AND variant = $2 AND consumed_timestamp IS NOT NULL ORDER BY created DESC"
        )
        .bind(&self.item)
        .bind(&self.variant)
        .fetch_all(get_pg!()).await.unwrap()
        };
        res.into_iter().map(|x| x.0.to_string()).collect()
    }

    pub async fn demand(uuid: &uuid::Uuid, price: f64, destination: &str) -> Option<Transaction> {
        // check if transaction exists
        let t = Transaction::get(uuid).await?;
        Some(t.consume(price, destination).await)
    }

    /// Records a supply transaction in the database.
    ///
    /// # Arguments
    ///
    /// * `price` - The price of the supplied items.
    /// * `origin` - The origin or source of the supplied items.
    ///
    /// # Returns
    ///
    /// Returns a UUID string representing the transaction.
    pub async fn supply(
        &self,
        price: f64,
        origin: Option<&str>,
        location: Option<&str>,
        note: Option<&str>,
    ) -> Transaction {
        Transaction::new(&self.item, &self.variant, price, origin, location, note).await
    }

    /// Returns all Transactions of this Item Variant
    pub async fn get_all_transactions(&self) -> Vec<Transaction> {
        sqlx::query_as(
            "SELECT * FROM transactions WHERE item = $1 AND variant = $2 ORDER BY created DESC",
        )
        .bind(&self.item)
        .bind(&self.variant)
        .fetch_all(get_pg!())
        .await
        .unwrap()
    }

    pub async fn get_transaction_timeslice(&self, year: i32, month: u32) -> Vec<Transaction> {
        let (start, end) = timestamp_range(year, month);

        sqlx::query_as("SELECT * FROM transactions WHERE created BETWEEN to_timestamp($1) AND to_timestamp($2) ORDER BY created DESC")
        .bind(start)
        .bind(end)
        .fetch_all(get_pg!()).await.unwrap()
    }

    pub async fn get_unique_origins(&self) -> Vec<String> {
        let res: Vec<(String,)> = sqlx::query_as("SELECT DISTINCT(origin) FROM transactions WHERE origin NOT LIKE 'flow::%' AND item = $1 AND variant = $2")
        .bind(&self.item)
        .bind(&self.variant)
        .fetch_all(get_pg!()).await.unwrap();
        res.into_iter().map(|x| x.0).collect()
    }

    pub async fn get_unique_destinations(&self) -> Vec<String> {
        let res: Vec<(String,)> = sqlx::query_as("SELECT DISTINCT(destination) FROM transactions WHERE destination NOT LIKE 'flow::%' AND item = $1 AND variant = $2")
        .bind(&self.item)
        .bind(&self.variant)
        .fetch_all(get_pg!()).await.unwrap();
        res.into_iter().map(|x| x.0).collect()
    }

    pub async fn price_history_by_origin(&self, origin: &str, limit: Option<i64>) -> Vec<f64> {
        let res: Vec<(f64,)> = sqlx::query_as(
            &format!("SELECT price FROM transactions WHERE item = $1 AND variant = $2 AND origin = $3 ORDER BY created DESC {}", if let Some(limit) = limit {
                format!("LIMIT {limit}")
            } else { String::new() })
        )
        .bind(&self.item)
        .bind(&self.variant)
        .bind(origin)
        .fetch_all(get_pg!()).await.unwrap();
        res.into_iter().map(|x| x.0).collect()
    }

    pub async fn get_latest_price(&self, origin: Option<String>) -> f64 {
        if let Some(origin) = origin {
            let res: (f64,) = sqlx::query_as("SELECT price FROM transactions WHERE item = $1 AND variant = $2 AND origin = $3 ORDER BY created DESC LIMIT 1")
            .bind(&self.item)
            .bind(&self.variant)
            .bind(origin)
            .fetch_one(get_pg!()).await.unwrap();
            res.0
        } else {
            let res: (f64,) = sqlx::query_as("SELECT price FROM transactions WHERE item = $1 AND variant = $2 ORDER BY created DESC LIMIT 1")
            .bind(&self.item)
            .bind(&self.variant)
            .bind(origin)
            .fetch_one(get_pg!()).await.unwrap();
            res.0
        }
    }

    /// Check if item variant is below minimum. Returns if this is the case and the number needed to fulfill minimum
    pub async fn is_below_min(&self) -> (bool, i64) {
        if let Some(min) = self.min {
            let amount = self.inventory().await.len() as i64;
            if amount < min {
                return (true, min - amount);
            }
        }

        (false, 0)
    }

    pub async fn stat(&self, full: bool) -> serde_json::Value {
        let active_transactions = self.inventory().await;

        let total_price: f64 = active_transactions.iter().map(|x| x.price).sum();

        if !full {
            return json!({
                "amount": active_transactions.len(),
                "total_price": total_price
            });
        }

        let all_transactions: Vec<Transaction> = sqlx::query_as(
            "SELECT * FROM transactions WHERE item = $1 AND variant = $2 ORDER BY created DESC",
        )
        .bind(&self.item)
        .bind(&self.variant)
        .fetch_all(get_pg!())
        .await
        .unwrap();

        let mut expired_count = 0.0;

        for t in &all_transactions {
            if t.is_expired().await {
                expired_count += 1.0;
            }
        }

        let expiry_rate = expired_count / all_transactions.len() as f64;
        let mut origin_stat = HashMap::new();

        for origin in self.get_unique_origins().await {
            let transactions_from_origin = active_transactions
                .iter()
                .filter(|x| x.origin.as_ref().map(|x| *x == origin).unwrap_or(false))
                .collect::<Vec<_>>();

            let prices = self
                .price_history_by_origin(&origin, None)
                .await
                .into_iter()
                .map(|x| x)
                .collect::<Vec<_>>();
            let prices_len = prices.len() as f64;
            let prices_summed = prices.into_iter().reduce(|acc, e| acc + e).unwrap_or(0.0);

            let stat_json = json!({
                "average_price": prices_summed / prices_len,
                "inventory": transactions_from_origin.len()
            });

            origin_stat.insert(origin, stat_json);
        }

        json!({
                "amount": active_transactions.len(),
                "total_price": total_price,
                "expiry_rate": expiry_rate,
                "origins": origin_stat
        })
    }

    pub fn api_json(&self) -> serde_json::Value {
        json!({
            "item": self.item,
            "variant": self.variant,
            "name": self.name,
            "min": self.min,
            "expiry": self.expiry,
            "barcodes": self.barcodes
        })
    }
}