/* Imports*/
import React from 'react';
import { numToAlphabeticalString, formatLargeOrSmall, avg } from "../lib/utils.js"

/* Functions */

const pathPlusLink = (pathSoFar, link) => {
    return [...pathSoFar, link]
    // previously: pathSoFar.concat(link).flat()
    // Note that concat is not destructive
    // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/concat
}

async function findPathsWithoutPrunning({
    sourceElementId, targetElementId,
    maxLengthOfPath, pathSoFar,
    links, nodes
}) {
    // This is an un-used function which might make findPaths more understandable
    // It uses the same recursive functionality 
    // but has no path prunning
    let paths = []

    /* Path traversing */
    if (maxLengthOfPath > 0) {
        for (let link of links) { // vs let link of linksNow in findPaths
            if (
                ((link.source == sourceElementId) && (link.target == targetElementId)) ||
                ((link.source == targetElementId) && (link.target == sourceElementId))
            ) { // direct Path
                let newPath = pathPlusLink(pathSoFar, link)
                paths.push(newPath)
            } else if ((link.source == sourceElementId)) {
                let newPaths = await findPaths({
                    pathSoFar: pathPlusLink(pathSoFar, link),
                    maxLengthOfPath: (maxLengthOfPath - 1),
                    sourceElementId: link.target,
                    targetElementId,
                    links: links, // vs let link of linksInner in findPaths
                    nodes
                })
                if (newPaths.length != 0) { 
                    paths.push(...newPaths)
                }
            } else if ((link.target == sourceElementId)) {
                let newPaths = await findPaths({
                    pathSoFar: pathPlusLink(pathSoFar, link),
                    maxLengthOfPath: (maxLengthOfPath - 1),
                    sourceElementId: link.source,
                    targetElementId,
                    links: links, // vs let link of linksInner in findPaths
                    nodes
                })
                if (newPaths.length != 0) {
                    paths.push(...newPaths)
                }
            }
        }
    }

    return paths
}

async function findPaths({
    sourceElementId, sourceElementPosition,
    targetElementId, targetElementPosition,
    maxLengthOfPath, pathSoFar,
    links, nodes
}) {
    // This is the key path finding function
    // It finds the path from one element to another, recursively
    // It used to be very computationally expensive until I added
    // the path prunning step: Instead of traversing all links,
    // traverse only those which are between the origin and target links
    // this requires us to have a notion of "between"

    let paths = []

    /* Path prunning*/
    let minPos = Math.min(sourceElementPosition, targetElementPosition)
    let maxPos = Math.max(sourceElementPosition, targetElementPosition)
    let linksInner = links.filter(link =>
        (minPos <= link.sourceElementPosition && link.sourceElementPosition <= maxPos) &&
        (minPos <= link.targetElementPosition && link.targetElementPosition <= maxPos)
    )
    let linksNow = linksInner.filter(link => (link.source == sourceElementId || link.target == sourceElementId))

    /* Path traversing */
    if (maxLengthOfPath > 0) {
        for (let link of linksNow) {
            if (
                ((link.source == sourceElementId) && (link.target == targetElementId)) ||
                ((link.source == targetElementId) && (link.target == sourceElementId))
            ) { // direct Path
                let newPath = pathPlusLink(pathSoFar, link)
                paths.push(newPath)
            } else if ((link.source == sourceElementId)) {
                let newPaths = await findPaths({
                    pathSoFar: pathPlusLink(pathSoFar, link),
                    maxLengthOfPath: (maxLengthOfPath - 1),
                    sourceElementPosition: link.sourceElementPosition,
                    sourceElementId: link.target,
                    targetElementId, targetElementPosition,
                    links: linksInner,
                    nodes
                })
                if (newPaths.length != 0) {
                    paths.push(...newPaths)
                }
            } else if ((link.target == sourceElementId)) {
                let newPaths = await findPaths({
                    pathSoFar: pathPlusLink(pathSoFar, link),
                    maxLengthOfPath: (maxLengthOfPath - 1),
                    sourceElementPosition: link.sourceElementPosition,
                    sourceElementId: link.source,
                    targetElementPosition,
                    targetElementId,
                    links: linksInner,
                    nodes
                })
                if (newPaths.length != 0) {
                    paths.push(...newPaths)
                }
            }
        }
    }

    return paths
}

async function findDistance({
    sourceElementId, sourceElementPosition,
    targetElementId, targetElementPosition,
    nodes, links
}) {
    // This function gets all possible paths using findPaths
    // then orders them correctly in the for loop 
    // (by flipping the distance to 1/distance when necessary)
    // and then gets the array of weights for the different paths.
    console.log(`findDistance@findPaths.js from ${sourceElementPosition} to ${targetElementPosition}`)

    let maxLengthOfPath = Math.abs(sourceElementPosition - targetElementPosition)
    let paths = await findPaths({
        sourceElementId, sourceElementPosition,
        targetElementId, targetElementPosition,
        links, nodes,
        maxLengthOfPath, pathSoFar: []
    });

    let weights = []
    for (let path of paths) {
        let currentSource = sourceElementId
        let weight = 1
        for (let element of path) {
            let distance = 0
            if (element.source == currentSource) {
                distance = element.distance
                currentSource = element.target
            } else if (element.target == currentSource) {
                distance = 1 / Number(element.distance)
                currentSource = element.source
            }
            weight = weight * distance

        }
        weights.push(weight)
    }
    return weights
}

async function findDistancesForAllElements({ nodes, links }) {
    // Simple wrapper function around findDistance
    // Needs to find the reference point first
    console.log("findDistancesForAllElements@findPaths.js")
    /* Get or build reference element */
    let referenceElements = nodes.filter(x => x.isReferenceValue)
    let midpoint = Math.round(nodes.length / 2)
    let referenceElement = referenceElements.length > 0 ? referenceElements[0] : nodes[midpoint]
    console.log(`referenceElement.position: ${referenceElement.position}`)

    /* Get distances. */
    let distances = nodes.map(node => {
        if (node.isReferenceValue || (node.id == referenceElement.id)) {
            return [1]
        } else {
            console.log("node")
            console.log(node)
            let distance = findDistance({
                sourceElementId: referenceElement.id,
                sourceElementPosition: referenceElement.position,
                targetElementId: node.id,
                targetElementPosition: node.position,
                nodes: nodes,
                links: links,
            })
            return distance
        }
    })
    distances = await Promise.all(distances)
    return distances
}

export async function buildRows({ isListOrdered, orderedList, listOfElements, links, rows, setTableRows }) {
    console.log("buildRows@findPaths.js")
    // This function is used in pages/comparisonView.js to create the rows that will be displayed.
    // it is in there because it needs to be deployed after isListOrdered becomes true,
    // and using an useEffect inside CreateTable was too messy.
    if (isListOrdered && !(orderedList.length < listOfElements.length) && rows.length == 0) {
        let nodes = []
        let positionDictionary = ({})
        orderedList.forEach((id, pos) => {
            nodes.push({ ...listOfElements[id], position: pos })
            positionDictionary[id] = pos
        })
        links = links.map(link => ({
            ...link,
            sourceElementPosition: positionDictionary[link.source],
            targetElementPosition: positionDictionary[link.target]
        }))

        let distances = await findDistancesForAllElements({ nodes, links })
        rows = nodes.map((element, i) => ({
            id: numToAlphabeticalString(element.position),
            position: element.position,
            name: element.name,
            distances: distances[i]
        }))
        console.log(rows)
        setTableRows(rows)
    }
}

export function CreateTable({ tableRows }) {
    /* This function receives a list of rows, and displays them nicely. */
    function abridgeArrayAndDisplay(array) {
        let newArray
        let formatForDisplay
        if (array.length > 10) {
            newArray = array.slice(0, 9)
            formatForDisplay = newArray.map(d => formatLargeOrSmall(d))
            formatForDisplay[9] = "..."
        } else {
            newArray = array
            formatForDisplay = newArray.map(d => formatLargeOrSmall(d))
        }
        let result = JSON.stringify(formatForDisplay, null, 2).replaceAll(`"`, "")
        return result
    }
    return (
        <div>
            <table className="">
                <thead>
                    <tr >
                        <th >Id</th>
                        <th>&nbsp;&nbsp;&nbsp;</th>
                        <th >Position</th>
                        <th>&nbsp;&nbsp;&nbsp;</th>
                        <th >Element</th>
                        <th> &nbsp;&nbsp;&nbsp;</th>
                        <th >Possible relative values</th>
                        <th> &nbsp;&nbsp;&nbsp;</th>
                        <th >Average relative value</th>
                    </tr>
                </thead>
                <tbody>
                    {tableRows.map(row => <tr key={row.id}>
                        <td className="" >{row.id}</td>
                        <td>&nbsp;&nbsp;&nbsp;</td>
                        <td className="" >{row.position}</td>
                        <td>&nbsp;&nbsp;&nbsp;</td>
                        <td className="">{row.name}</td>
                        <td>&nbsp;&nbsp;&nbsp;</td>
                        <td className="">{abridgeArrayAndDisplay(row.distances)}</td>
                        <td>&nbsp;&nbsp;&nbsp;</td>
                        <td className="">{formatLargeOrSmall(avg(row.distances))}</td>
                    </tr>
                    )}
                </tbody>
            </table>
        </div>
    )

}

/* Testing */
//import fs from 'fs';
//import path from 'path';
/*
const directory = path.join(process.cwd(),"pages")
let links = JSON.parse(fs.readFileSync(path.join(directory, 'distancesExample.json'), 'utf8'));
let nodes = JSON.parse(fs.readFileSync(path.join(directory, 'listOfPosts.json'), 'utf8'));

let paths = findPaths({sourceElementId:2, targetElementId:0, pathSoFar: [], links, nodes, maxLengthOfPath: 2})
console.log(JSON.stringify(paths, null, 2))
*/
/*
let paths = findPaths({sourceElementId:2, targetElementId:0, links, nodes})
console.log(JSON.stringify(paths, null, 2))
*/
/*
let distances = findDistance({sourceElementId:2, targetElementId:4, links, nodes})
console.log(distances)
*/