type Game = { name: string, rating: number }
const listOfgame:Game[] =[
{name:'redalert' , rating:50},
{name:'devilcry', rating:2},
{name:'dota2', rating:3},
{name:'dota2',rating:5}
]


// 1. returns list of name from list of game
const names = (games: Game[]): string[] => games.map((game) => game.name)
console.log(names(listOfgame))


// 2. returns list of string that has format `<name> [<rating>]`
// eg. `call of duty [7.4]`

const formatGames = (games: Game[]): string[] => games.map((game) => {
     return `${game.name} [${game.rating}]`
})
console.log(formatGames(listOfgame))
// 3. get sum of all the ratings in list of game
const totalRatingsOf = (games: Game[]): number => games.reduce((sum,game) =>{
    return sum + game.rating
}, 0)

console.log(totalRatingsOf(listOfgame))

// 4. get average of all the ratings in list of game
const averageRatingsOf = (games: Game[]): number => games.reduce((sumaverage,game) => {

return  sumaverage + game.rating

}, 0)/games.length
console.log(averageRatingsOf(listOfgame))
// 5. get total rating by name from list of game
const totalRatingsByName = (name: string, games: Game[]): number =>
totalRatingsOf(games.filter( game => game.name === name  )  )


console.log(totalRatingsByName('dota2',listOfgame))

// 6. get total rating by name from list of game
const averageRatingsByName = (name: string, games: Game[]): number => totalRatingsOf(games.filter( game =>
    game.name === name
    ))/games.length
    console.log(averageRatingsByName('dota2',listOfgame))

// 7. increase rating for all games
const increaseRatingBy = (inc: number, games: Game[]): Game[] =>

games.map((game) =>  {return { name: game.name, rating:game.rating + inc }  } )


console.log(increaseRatingBy(1,listOfgame))
// 8. decrease rating for game with specific name
const decreaseRatingBy = (dec: number, name: string, games: Game[]): Game[] =>

games.filter((game => game.name === name )).map((game =>  {
    return{
        name: game.name,
        rating: game.rating - dec
    }
}

))


console.log(decreaseRatingBy(20,'redalert',listOfgame))

// 9. returns game if the name exist else returns undefined
const findByName = (name: string, games: Game[]): Game[] => games.reduce((game => {


    return   game.name=== name  ?game :'undefined'}

}))


// const findByName = (name: string, games: Game[]): Game[] => games.filter(game =>{


//     if( game.name === name )  {
//         return game
//     }
//     else {return undefined
//     }


// })



console.log(findByName('redaledrt',listOfgame))

// 10. decrease rating for game that has name in the list
const decreaseRatingForNames = (dec: number, names: string[], games: Game[]): Game[] =>

games.filter((game => game.name === names )).map((game =>  {
    return{
        name: game.name,
        rating: game.rating - dec
    }
}

))


console.log(decreaseRatingForNames(6734,'dota2',listOfgame))