console.clear()

function splitStringAtSeparator(str, separator) {
    const separatorIndex = str.indexOf(separator)
    if (separatorIndex === -1) {
        return [str, '']
    } else {
        const beforeSeparator = str.slice(0, separatorIndex)
        const afterSeparator = str.slice(separatorIndex + separator.length)
        return [beforeSeparator, afterSeparator]
    }
}

const REGISTRY = {}

const compileNewVector = (length, params, componentFn) => {
    const label = `vector<${length}>(${componentFn.toString()})`
    // console.log(`requested function for "${label}"`)

    let fn = REGISTRY[label]
    if (!fn) {
        const [varsRaw, codeRaw] = splitStringAtSeparator(componentFn.toString(), '=>')
        const freeIndex = varsRaw.replace(/[()]/g, '').trim()
        const code = codeRaw.trim()

        // console.log('compiling...')

        let source = `const out = Array(${length});\n`
        for (let i = 0; i < length; i++) {
            source += `out[${i}] = ${code.replaceAll(freeIndex, i)};\n`
        }
        source += `return out;`
        // console.log(`=> Source: "${source.replaceAll('\n', ' ')}"`)

        fn = new Function(...Object.keys(params), source)
        REGISTRY[label] = fn
    } else {
        // console.log('using cached')
    }

    return fn(...Object.values(params))
}

const compileSum = (length, params, componentFn) => {
    const label = `sum<${length}>(${componentFn.toString()})`
    // console.log(`requested function for "${label}"`)

    let fn = REGISTRY[label]
    if (!fn) {
        const [varsRaw, codeRaw] = splitStringAtSeparator(componentFn.toString(), '=>')
        const freeIndex = varsRaw.replace(/[()]/g, '').trim()
        const code = codeRaw.trim()

        // console.log('compiling...')

        let source = `let out = 0;\n`
        for (let i = 0; i < length; i++) {
            source += `out += ${code.replaceAll(freeIndex, i)};\n`
        }
        source += `return out;`
        // console.log(`=> Source: "${source.replaceAll('\n', ' ')}"`)

        fn = new Function(...Object.keys(params), source)
        REGISTRY[label] = fn
    } else {
        // console.log('using cached')
    }

    return fn(...Object.values(params))
}

const operators = {
    ['+'](v, w) {
        return compileNewVector(v.length, { v, w }, i => v[i] + w[i])
    },
    ['*'](v, w) {
        return compileNewVector(v.length, { v, w }, i => v[i] * w[i])
    },
    ['-'](v, w) {
        return compileNewVector(v.length, { v, w }, i => v[i] - w[i])
    },
    ['/'](v, w) {
        return compileNewVector(v.length, { v, w }, i => v[i] / w[i])
    },
    ['dot'](v, w) {
        const vw = operators['*'](v, w)
        return compileSum(v.length, { vw }, i => vw[i])
    },
}

export const m = (fragments, ...args) => {
    const opName = fragments[1].trim()
    return operators[opName](...args)
}

const v1 = [1, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3]
const w1 = [2, 3, 4, 3, 4, 3, 4, 3, 4, 3, 4, 3, 4, 3, 4, 3, 4, 3, 4, 3, 4, 3, 4, 3, 4, 3, 4, 3, 4, 3, 4]
const v2 = [1, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3]
const w2 = [2, 3, 4, 3, 4, 3, 4, 3, 4, 3, 4, 3, 4]

function dotVectors(v, w) {
    return v.map((vi, i) => vi * w[i]).reduce((acc, vw) => acc + vw, 0)
}

// Benchmarking code
const iterations = 50000

for (let i = 0; i < 10; i++) {
    const start = performance.now()
    let result
    for (let i = 0; i < iterations; i++) {
        result = i % 2 === 0 ? m`${v1} dot ${w1}` : m`${v2} dot ${w2}`
    }
    const end = performance.now()
    console.log(`Time for ${iterations} iterations: ${end - start}ms`)
}

console.log('----------')

for (let i = 0; i < 10; i++) {
    const start = performance.now()
    let result
    for (let i = 0; i < iterations; i++) {
        result = i % 2 === 0 ? dotVectors(v1, w1) : dotVectors(v2, w2)
    }
    const end = performance.now()
    console.log(`Time for ${iterations} iterations: ${end - start}ms`)
}