package main

import (
	"context"
	"time"

	"github.com/jackc/pgx/v5"
	"github.com/jackc/pgx/v5/pgxpool"
)

var dbConn *pgxpool.Pool

func DbInit(ctx context.Context) {
	var err error
	dbConn, err = pgxpool.New(ctx, "postgres://master:secret@localhost:5432") // TODO change to env in production
	if err != nil {
		panic(err)
	}

	_, err = dbConn.Exec(ctx, `
		CREATE TABLE IF NOT EXISTS users (
		    id SERIAL PRIMARY KEY,
		    name VARCHAR(20) UNIQUE NOT NULL,
		    pass_hash VARCHAR(60) NOT NULL,
		    pronouns VARCHAR(15) DEFAULT NULL,
		    color_red SMALLINT DEFAULT NULL,
		    color_green SMALLINT DEFAULT NULL,
		    color_blue SMALLINT DEFAULT NULL,
		    created_at TIMESTAMP NOT NULL DEFAULT NOW()
		)
	`)
	if err != nil {
		panic(err)
	}

	_, err = dbConn.Exec(ctx, `
		CREATE TABLE IF NOT EXISTS chat_groups (
		    id SERIAL PRIMARY KEY,
		    name VARCHAR(48) NOT NULL,
		    creator_id INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
		    owner_id INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
		    enable_client_colors BOOLEAN NOT NULL DEFAULT true,
		    color_red SMALLINT DEFAULT NULL,
		    color_green SMALLINT DEFAULT NULL,
		    color_blue SMALLINT DEFAULT NULL,
		    created_at TIMESTAMP NOT NULL DEFAULT NOW()
		)
	`)
	if err != nil {
		panic(err)
	}

	_, err = dbConn.Exec(ctx, `
		CREATE TABLE IF NOT EXISTS chat_group_members (
			group_id INTEGER NOT NULL REFERENCES chat_groups(id) ON DELETE CASCADE,
			user_id  INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
			joined_at TIMESTAMP NOT NULL DEFAULT NOW(),
			PRIMARY KEY (group_id, user_id)
		)
	`)
	if err != nil {
		panic(err)
	}
}

// DbUserSaveWithoutGroups saves user in db without groups and sets its id
// return: error if not successful
func DbUserSaveWithoutGroups(ctx context.Context, user *User) error {
	err := dbConn.QueryRow(ctx, `
        INSERT INTO users (name, pass_hash, pronouns, color_red, color_green, color_blue, created_at)
        VALUES ($1, $2, $3, $4, $5, $6, $7)
        RETURNING id
    `, user.Name, user.PasswordHash, user.Pronouns, user.Color[0], user.Color[1], user.Color[2], user.CreatedAt).
		Scan(&user.Id)
	return err
}

// DbUserDelete deletes given user by id
// return: error if not successful
func DbUserDelete(ctx context.Context, id uint32) error {
	_, err := dbConn.Exec(ctx, `
		DELETE FROM users WHERE id = $1
	`, id)
	return err
}

// DbUserSetByName sets all fields of given struct with database's data using name
// return: error if not successful
func DbUserSetByName(ctx context.Context, user *User) error {
	err := dbConn.QueryRow(ctx, `
		SELECT id, name, pass_hash, pronouns, color_red, color_green, color_blue, created_at FROM users WHERE name = $1
	`, user.Name).Scan(&user.Id, &user.Name, &user.PasswordHash, &user.Pronouns, &user.Color[0], &user.Color[1], &user.Color[2], &user.CreatedAt)
	if err != nil {
		return err
	}
	return DbUserSetGroups(ctx, user)
}

// DbUserSetByIdWithoutGroups sets all fields of given struct with database's data using id, excluding groups
// return: error if not successful
func DbUserSetByIdWithoutGroups(ctx context.Context, user *User) error {
	err := dbConn.QueryRow(ctx, `
		SELECT name, pass_hash, pronouns, color_red, color_green, color_blue, created_at FROM users WHERE id = $1
	`, user.Id).Scan(&user.Name, &user.PasswordHash, &user.Pronouns, &user.Color[0], &user.Color[1], &user.Color[2], &user.CreatedAt)
	return err
}

// DbUserSetById sets all fields of given struct with database's data using id, including groups
// return: error if not successful
func DbUserSetById(ctx context.Context, user *User) error {
	err := DbUserSetByIdWithoutGroups(ctx, user)
	if err != nil {
		return err
	}
	return DbUserSetGroups(ctx, user)
}

// DbUserSetGroups populates user's Groups map with ids of all groups the user belongs to from database
// return: error if not successful
func DbUserSetGroups(ctx context.Context, user *User) error {
	rows, err := dbConn.Query(ctx, `
		SELECT group_id FROM chat_group_members WHERE user_id = $1
	`, user.Id)
	if err != nil {
		return err
	}
	defer rows.Close()

	user.Groups = make(map[uint32]struct{})
	for rows.Next() {
		var groupId uint32
		if err := rows.Scan(&groupId); err != nil {
			return err
		}
		user.Groups[groupId] = struct{}{}
	}
	return rows.Err()
}

// DbGroupSetColor set group's color based on id
// return: error if not successful
func DbGroupSetColor(ctx context.Context, group *Group) error {
	_, err := dbConn.Exec(ctx, `
		UPDATE chat_groups SET color_red = $1, color_green = $2, color_blue = $3 WHERE id = $4
	`, group.Color[0], group.Color[1], group.Color[2], group.Id)

	return err
}

// DbGroupSaveWithoutUsers saves group in db and sets its id, also adds the owner as first member
// return: error if not successful
func DbGroupSaveWithoutUsers(ctx context.Context, group *Group) error {
	err := dbConn.QueryRow(ctx, `
		INSERT INTO chat_groups (name, creator_id, owner_id, enable_client_colors, color_red, color_green, color_blue, created_at)
		VALUES ($1, $2, $3, $4, $5, $6, $7, $8)
		RETURNING id
	`, group.Name, group.CreatorId, group.OwnerId, group.EnableUserColors, group.Color[0], group.Color[1], group.Color[2], group.CreatedAt).
		Scan(&group.Id)
	if err != nil {
		return err
	}
	_, err = dbConn.Exec(ctx, `
		INSERT INTO chat_group_members (group_id, user_id, joined_at)
		VALUES ($1, $2, $3)
	`, group.Id, group.OwnerId, group.CreatedAt)
	return err
}

// DbGroupDelete deletes given group by id
// return: error if not successful
func DbGroupDelete(ctx context.Context, group *Group) error {
	_, err := dbConn.Exec(ctx, `
		DELETE FROM chat_groups WHERE id = $1
	`, group.Id)
	return err
}

// DbGroupSetWithoutUsersById sets all fields of given struct with database's data using id, populates Users map with member ids but not their data
// return: error if not successful
func DbGroupSetWithoutUsersById(ctx context.Context, group *Group) error {
	err := dbConn.QueryRow(ctx, `
		SELECT name, creator_id, owner_id, enable_client_colors, color_red, color_green, color_blue, created_at FROM chat_groups WHERE id = $1
	`, group.Id).Scan(&group.Name, &group.CreatorId, &group.OwnerId, &group.EnableUserColors, &group.Color[0], &group.Color[1], &group.Color[2], &group.CreatedAt)
	if err != nil {
		return err
	}

	rows, err := dbConn.Query(ctx, `
		SELECT user_id FROM chat_group_members WHERE group_id = $1
	`, group.Id)
	if err != nil {
		return err
	}
	defer rows.Close()

	group.Users = make(map[uint32]struct{})
	for rows.Next() {
		var userId uint32
		if err := rows.Scan(&userId); err != nil {
			return err
		}
		group.Users[userId] = struct{}{}
	}
	return rows.Err()
}

// DbGroupSetById sets all fields of given struct with database's data using id, including full member user data
// return: error if not successful
func DbGroupSetById(ctx context.Context, group *Group) error {
	err := DbGroupSetWithoutUsersById(ctx, group)
	if err != nil {
		return err
	}
	return DbGroupSetMembers(ctx, group)
}

// DbGroupSetMembers populates group's Users map with ids of all members from database
// return: error if not successful
func DbGroupSetMembers(ctx context.Context, group *Group) error {
	rows, err := dbConn.Query(ctx, `
		SELECT user_id FROM chat_group_members WHERE group_id = $1
	`, group.Id)
	if err != nil {
		return err
	}
	defer rows.Close()

	group.Users = make(map[uint32]struct{})
	for rows.Next() {
		var userId uint32
		if err := rows.Scan(&userId); err != nil {
			return err
		}
		group.Users[userId] = struct{}{}
	}
	return rows.Err()
}

// DbGroupAddUsers adds given users to group in db, silently ignores already existing members
// return: error if not successful
func DbGroupAddUsers(ctx context.Context, groupId uint32, userIds *[MaxUsersInGroup]uint32) error {
	batch := &pgx.Batch{}
	now := time.Now()
	var count int
	for _, uid := range userIds {
		if uid == 0 {
			continue
		}
		batch.Queue(`
			INSERT INTO chat_group_members (group_id, user_id, joined_at)
			VALUES ($1, $2, $3)
			ON CONFLICT DO NOTHING
		`, groupId, uid, now)
		count++
	}
	br := dbConn.SendBatch(ctx, batch)
	defer br.Close()
	for range count {
		if _, err := br.Exec(); err != nil {
			return err
		}
	}
	return nil
}

// DbGroupRemoveUsers removes given users from group in db, silently ignores not existing members
// return: deleted users count, error if not successful
func DbGroupRemoveUsers(ctx context.Context, groupId uint32, userIds *[MaxUsersInGroup]uint32) (int, error) {
	batch := &pgx.Batch{}
	var count int
	for _, uid := range userIds {
		if uid == 0 {
			continue
		}
		batch.Queue(`
			DELETE FROM chat_group_members WHERE group_id = $1 AND user_id = $2
		`, groupId, uid)
		count++
	}
	br := dbConn.SendBatch(ctx, batch)
	defer br.Close()
	var deleted int
	for range count {
		tag, err := br.Exec()
		if err != nil {
			return deleted, err
		}
		deleted += int(tag.RowsAffected())
	}
	return deleted, nil
}

// DbGroupSetOwnerId set group's owner based on id
// return: error if not successful
func DbGroupSetOwnerId(ctx context.Context, group *Group) error {
	_, err := dbConn.Exec(ctx, `
		UPDATE chat_groups SET owner_id = $1 WHERE id = $2
	`, group.OwnerId, group.Id)

	return err
}