"usestrict";

// OBJECTIVE ////////////////////////////////////////////////////////////////////////////////////////////////

// 1. dividing an array into chunks of a certain size.

// SUMMARY //////////////////////////////////////////////////////////////////////////////////////////////////

// What is the problem?:

// 1. Given an array and chunck size, divide the array into many subarrays where each subarray is of length size.

// -- example:

// chunk([1,2,3,4],2) --> [[1,2][3,4]]

// chunk([1,2,3,4,5], 2) --> [[1,2],[3,4],[5]]

// chunk([1,2,3,4,5,6,7,8], 3) --> [[1,2,3],[4,5,6],[7,8]]

// chunk([1,2,3,4,5], 4) --> [[1,2,3,4],[5]]

// chunk([1,2,3,4,5], 10) --> [[1,2,3,4,5]]

// What is the BEST solution?

// 1. solution 1 for now.

// What are the special components of these solutions?:

// 1. for ...of loop

// 2. .slice() method

// What needs work?

// 1. the result of the chunked arrays seems to be a bit off compared to the examples, need to look into it.

//////////////////////////////////////////////////////////////////////////////////////////////////////////////

// Basic overview of the problem

// You are given this:

//

// chunk([1,2,3,4],2) --> [[1,2][3,4]]

//

// Suppose we are asked to call chunk with an array of 4 numbers (i.e. [1,2,3,4] and a spcific chunk length of 2 (passed in as the chunk size),

// we'll end up with a big array with 2 smaller arrays inside it, spcifically [[1,2][3,4]].

///// SOLUTION 1 ///////////////////////////////////////////////////////////////////////////

function chunk(array, size) {

const chunked = [];

for (let element of array) {

const last = chunked[chunked.length - 1];

if (!last || last.length === size) {

chunked.push([element]);

} else {

last.push([element])

}

}

return chunked;

}

console.log("solution 1")

console.log(chunk([1,2,3,4], 2))

/*

// SOLUTION 1 ///////////////////////////////////////////////////////////////

// To solve the problem, we need to lay out our plan:

// 1. Create an empty array to hold chunks of data.

// 2. For each element in the 'unchunked' array...

// 3. retrieve the last element in 'chunked'.

// 4. If last element does not exist, or if its length is equal to chunk size...

// 5. Push a new chunk into 'chunked' with the current element.

// 6. Else add the current element into the chunk.

function chunk(array, size) {

// new array that holds all the differen chunks of data

const chunked = [];

// next we setup a for...of loop to iterate through the array.

for (let element of array) {

//to get the last element in the chunked array, we create a temporary variable called "last" (i.e. last element in array).

// to get this we say "chunked at chunk.length minus 1".

const last = chunked[chunked.length - 1];

// if the last element doesnt exist OR the length is equal to the chunk size (in this case 2), then push element into chunked.

if (!last || last.length === size) {

chunked.push([element]);

// otherwise push into the temporary variable "last" (which will then feed into chunk if it can).

} else {

last.push([element])

}

}

// then we return the variable "chunked"

return chunked;

}

console.log(chunk([1,2,3,4], 2))

*/

///// SOLUTION 2 ///////////////////////////////////////////////////////////////////////////

function chunk2(array, size) {

const chunked = [];

const index = 0;

while(index < array.length) {

chunked.push(array.slice(index, index + size));

index += size;

}

return chunked;

}

console.log("solution 2")

console.log(chunk([1,2,3,4], 2))

/*

// solving with .slice()

// using the standard slice method is just applying the method and, in this case, stating the index 0 - 3 (note 3 is not included).

const letters = ["a","b","c","d","e"];

letters.slice(0,3) // ["a","b","c"]

// so the solution to solution 2 is as follows:

// 1. Create empty 'chunked' array.

// 2. Create "index start at 0".

// 3. while index is less than array.length

// 4. push a slice of length 'size' from 'array' into 'chunked'.

// 5. add 'size' to 'index'.

function chunk2(array, size) {

const chunked = [];

// this is the index variable

const index = 0;

// then we setup our while loop which will run as long as the index is less than the orginal array.length.

while(index < array.length) {

// array.slice produces an array that contains some number of elements out of the orginal array

// the slice that is porduced goes straight into chunked using the push method.

chunked.push(array.slice(index, index + size));

index += size;

}

return chunked;

}

console.log("solution 2")

console.log(chunk([1,2,3,4], 2))

*/