use core::panic;
use std::io;
use chrono::{offset::LocalResult, DateTime, Datelike, Duration, Local, TimeZone};
use sqlx::PgPool;
use std::sync::Arc;
use time::OffsetDateTime;
use std::sync::Mutex;

#[derive(Debug)]
struct Hospital {
    id: i32,
    name: String,
}

// struct Schedule {
//     from: DateTime<chrono_tz::Tz>,
//     to: DateTime<chrono_tz::Tz>,
// }

// Helper function to print with timestamp
fn log_with_timestamp(message: &str) {
    let now = Local::now();
    println!("[{}] {}", now.format("%Y-%m-%d %H:%M:%S"), message);
}

// Static variable to store the last printed hospital ID
static LAST_HOSPITAL_ID: Mutex<Option<i32>> = Mutex::new(None);

pub async fn create_hospital_list(pool: Arc<PgPool>) -> Result<(), sqlx::Error> {
    // Fetch hospitals from the database
    let hospitals = sqlx::query_as!(
        Hospital,
        r#"
        SELECT id, name FROM hospitals ORDER BY id
        "#
    )
    .fetch_all(&*pool)
    .await?;

    if hospitals.is_empty() {
        log_with_timestamp("No hospitals found in the database.");
        return Ok(());
    }

    // let mut start: DateTime<Local> = Local.with_ymd_and_hms(2025, 1, 6, 8, 0, 0).unwrap(); // set date for testing
    let mut start: DateTime<Local> = Local::now();
    let mut end: DateTime<Local> = get_end_of_shift(start);

    log_with_timestamp(&format!("It is now {} and the current Shift is ending on {}", 
        start.format("%A %d/%m/%Y %H:%M"), 
        end.format("%A %d/%m/%Y %H:%M")));
    log_with_timestamp("Which Hospital is currently on duty?");

    // print out the hospitals
    for hospital in &hospitals {
        log_with_timestamp(&format!("{}) {}", hospital.id, hospital.name));
    }

    let mut hospital_id_input = String::new();
    io::stdin()
        .read_line(&mut hospital_id_input)
        .expect("Failed to read the line");
    let hospital_id_input = hospital_id_input.trim();
    let hospital_id: i32 = match hospital_id_input.parse() {
        Ok(num) => num,
        Err(_) => {
            log_with_timestamp("Please enter a valid number!");
            return Ok(());
        }
    };
    
    // Find the index of the selected hospital
    let mut hospital_index: usize = 0;
    let mut found = false;
    for (i, hospital) in hospitals.iter().enumerate() {
        if hospital.id == hospital_id {
            hospital_index = i;
            found = true;
            break;
        }
    }
    
    if !found {
        log_with_timestamp(&format!("Hospital with ID {} not found.", hospital_id));
        return Ok(());
    }

    log_with_timestamp("Generating and storing shifts in the database...");
    
    // Clear existing shifts
    sqlx::query("DELETE FROM shifts")
        .execute(&*pool)
        .await?;
    
    // Generate and store 100 shifts
    for i in 1..=100 {
        // Format the timestamps as strings for database storage
        let start_str = start.format("%Y-%m-%d %H:%M:%S").to_string();
        let end_str = end.format("%Y-%m-%d %H:%M:%S").to_string();
        
        // Store the current shift in the database
        sqlx::query(
            r#"
            INSERT INTO shifts (hospital_id, start_time, end_time)
            VALUES ($1, $2::timestamp with time zone, $3::timestamp with time zone)
            "#,
        )
        .bind(hospitals[hospital_index].id)
        .bind(start_str)
        .bind(end_str)
        .execute(&*pool)
        .await?;
        
        // Print progress only every 10 shifts
        if i % 10 == 0 {
            log_with_timestamp(&format!("Stored {} shifts...", i));
        }

        // new shift
        start = end;
        end = get_end_of_shift(start);

        // change hospital
        hospital_index = if hospital_index == 0 { 1 } else { 0 };
        
        // If we only have one hospital, don't switch
        if hospitals.len() == 1 {
            hospital_index = 0;
        }
    }
    
    log_with_timestamp("Successfully stored 100 shifts in the database.");
    Ok(())
}

pub async fn check_and_create_future_shifts(pool: Arc<PgPool>) -> Result<(), sqlx::Error> {
    // Get the current time
    let now = Local::now();
    
    // Calculate the date two months from now
    let two_months_from_now = now + Duration::days(60);
    
    // Convert chrono DateTime to time OffsetDateTime for SQLx
    let now_offset = OffsetDateTime::from_unix_timestamp(now.timestamp())
        .expect("Failed to convert to OffsetDateTime");
    let two_months_offset = OffsetDateTime::from_unix_timestamp(two_months_from_now.timestamp())
        .expect("Failed to convert to OffsetDateTime");
    
    // Check if there are any shifts in the next two months
    let future_shifts_count = sqlx::query_scalar::<_, i64>(
        r#"
        SELECT COUNT(*) FROM shifts 
        WHERE start_time > $1 AND start_time < $2
        "#,
    )
    .bind(now_offset)
    .bind(two_months_offset)
    .fetch_one(&*pool)
    .await?;
    
    // If there are no future shifts, create them
    if future_shifts_count == 0 {
        log_with_timestamp("No future shifts found. Creating shifts for the next two months...");
        
        // Get the current hospital on duty
        let current_hospital = sqlx::query_as!(
            Hospital,
            r#"
            SELECT h.id, h.name 
            FROM hospitals h
            JOIN shifts s ON h.id = s.hospital_id
            WHERE s.end_time > $1
            ORDER BY s.end_time ASC
            LIMIT 1
            "#,
            now_offset
        )
        .fetch_optional(&*pool)
        .await?;
        
        // If no current hospital is found, get the first hospital from the database
        let hospital_id = match current_hospital {
            Some(hospital) => hospital.id,
            None => {
                let first_hospital = sqlx::query_as!(
                    Hospital,
                    r#"
                    SELECT id, name FROM hospitals ORDER BY id LIMIT 1
                    "#
                )
                .fetch_optional(&*pool)
                .await?
                .ok_or_else(|| sqlx::Error::RowNotFound)?;
                
                first_hospital.id
            }
        };
        
        // Find the index of the selected hospital
        let hospitals = sqlx::query_as!(
            Hospital,
            r#"
            SELECT id, name FROM hospitals ORDER BY id
            "#
        )
        .fetch_all(&*pool)
        .await?;
        
        let mut hospital_index = 0;
        for (i, hospital) in hospitals.iter().enumerate() {
            if hospital.id == hospital_id {
                hospital_index = i;
                break;
            }
        }
        
        // Generate shifts starting from now
        let mut start = now;
        let mut end = get_end_of_shift(start);
        
        // Generate shifts for the next two months (approximately 60 days)
        for _ in 1..=120 {
            // Convert chrono DateTime to time OffsetDateTime for SQLx
            let start_offset = OffsetDateTime::from_unix_timestamp(start.timestamp())
                .expect("Failed to convert to OffsetDateTime");
            let end_offset = OffsetDateTime::from_unix_timestamp(end.timestamp())
                .expect("Failed to convert to OffsetDateTime");
            
            // Store the current shift in the database
            sqlx::query(
                r#"
                INSERT INTO shifts (hospital_id, start_time, end_time)
                VALUES ($1, $2, $3)
                "#,
            )
            .bind(hospitals[hospital_index].id)
            .bind(start_offset)
            .bind(end_offset)
            .execute(&*pool)
            .await?;
            
            // new shift
            start = end;
            end = get_end_of_shift(start);
            
            // change hospital
            hospital_index = if hospital_index == 0 { 1 } else { 0 };
            
            // If we only have one hospital, don't switch
            if hospitals.len() == 1 {
                hospital_index = 0;
            }
        }
        
        log_with_timestamp("Successfully created future shifts for the next two months.");
    } else {
        log_with_timestamp(&format!("Found {} future shifts. No need to create more.", future_shifts_count));
    }
    
    Ok(())
}

pub async fn print_current_hospital(pool: Arc<PgPool>) -> Result<(), sqlx::Error> {
    // Get the current time
    let now = Local::now();
    
    // Convert chrono DateTime to time OffsetDateTime for SQLx
    let now_offset = OffsetDateTime::from_unix_timestamp(now.timestamp())
        .expect("Failed to convert to OffsetDateTime");
    
    // Get the current hospital on duty
    let current_hospital = sqlx::query_as!(
        Hospital,
        r#"
        SELECT h.id, h.name 
        FROM hospitals h
        JOIN shifts s ON h.id = s.hospital_id
        WHERE s.start_time <= $1 AND s.end_time > $1
        ORDER BY s.end_time ASC
        LIMIT 1
        "#,
        now_offset
    )
    .fetch_optional(&*pool)
    .await?;
    
    // Get the last printed hospital ID
    let mut last_id = LAST_HOSPITAL_ID.lock().unwrap();
    
    // Check if the hospital has changed
    let current_id = current_hospital.as_ref().map(|h| h.id);
    let has_changed = *last_id != current_id;
    
    // Only print if the hospital has changed
    if has_changed {
        match &current_hospital {
            Some(hospital) => {
                log_with_timestamp(&format!("Current hospital on duty: {} (ID: {})", hospital.name, hospital.id));
            },
            None => {
                log_with_timestamp("No hospital currently on duty.");
            }
        }
        
        // Update the last printed hospital ID
        *last_id = current_id;
    }
    
    Ok(())
}

fn get_end_of_shift(start: DateTime<Local>) -> DateTime<Local> {

    let end: DateTime<Local>;

    // define weekday & hour
    let weekday_str: String = start.format("%u").to_string();
    let weekday: u32 = weekday_str.parse().unwrap();
    let hour_str: String = start.format("%H").to_string();
    let hour: u32 = hour_str.parse().unwrap();

    // From Monday to Thursday before 7:00
    if weekday >= 1 && weekday <= 4 && hour < 7 {
        
        let next_day: DateTime<Local> = start;
        let year: i32 = next_day.year();
        let month: u32 = next_day.month();
        let day: u32 = next_day.day();
        
        let local_result: LocalResult<DateTime<Local>> = Local.with_ymd_and_hms(year, month, day, 7, 0, 0);
        end = match local_result {
            LocalResult::None => {
                panic!("The specified date and time do not exist.");
            },
            LocalResult::Single(datetime) => datetime,
            LocalResult::Ambiguous(datetime1, _datetime2, ) => {
                datetime1
            }
        };

    // From Monday to Wednesday after 7:00
    } else if weekday >= 1 && weekday <= 3 && hour >= 7 {

        let next_day: DateTime<Local> = start + Duration::days(1);
        let year: i32 = next_day.year();
        let month: u32 = next_day.month();
        let day: u32 = next_day.day();
        
        let local_result: LocalResult<DateTime<Local>> = Local.with_ymd_and_hms(year, month, day, 7, 0, 0);
        end = match local_result {
            LocalResult::None => {
                panic!("The specified date and time do not exist.");
            },
            LocalResult::Single(datetime) => datetime,
            LocalResult::Ambiguous(datetime1, _datetime2, ) => {
                datetime1
            }
        };

    } else if weekday == 4 && hour >= 7 {

        let next_day: DateTime<Local> = start + Duration::days(1);
        let year: i32 = next_day.year();
        let month: u32 = next_day.month();
        let day: u32 = next_day.day();
        
        let local_result: LocalResult<DateTime<Local>> = Local.with_ymd_and_hms(year, month, day, 17, 0, 0);
        end = match local_result {
            LocalResult::None => {
                panic!("The specified date and time do not exist.");
            },
            LocalResult::Single(datetime) => datetime,
            LocalResult::Ambiguous(datetime1, _datetime2, ) => {
                datetime1
            }
        };

    } else if weekday == 5 && hour < 17 {

        let next_day: DateTime<Local> = start;
        let year: i32 = next_day.year();
        let month: u32 = next_day.month();
        let day: u32 = next_day.day();
        
        let local_result: LocalResult<DateTime<Local>> = Local.with_ymd_and_hms(year, month, day, 17, 0, 0);
        end = match local_result {
            LocalResult::None => {
                panic!("The specified date and time do not exist.");
            },
            LocalResult::Single(datetime) => datetime,
            LocalResult::Ambiguous(datetime1, _datetime2, ) => {
                datetime1
            }
        };

    // Friday after 17:00
    } else {

        let count_days: i64 = 8 - weekday as i64;
        let next_day: DateTime<Local> = start + Duration::days(count_days);
        let year: i32 = next_day.year();
        let month: u32 = next_day.month();
        let day: u32 = next_day.day();
        
        let local_result: LocalResult<DateTime<Local>> = Local.with_ymd_and_hms(year, month, day, 7, 0, 0);
        end = match local_result {
            LocalResult::None => {
                panic!("The specified date and time do not exist.");
            },
            LocalResult::Single(datetime) => datetime,
            LocalResult::Ambiguous(datetime1, _datetime2, ) => {
                datetime1
            }
        };
    }
    
    end
}