import Frame from '../../data/Frame';

function calculateFrameElevation(frames: Frame[], tokenCountForEachLine: number[]):{elevationForEachFrame:number[],elevationsForEachLine:number[]} {

    // total number of tokens
    const tokenCount = tokenCountForEachLine.reduce((sum, x)=>sum+x,0);

    const elevationTable = initElevationTable(tokenCount);

    const elevationForEachFrame: number[] = [];

    const elevationsForEachLine: number[] = [];

    for(const frame of frames) {
         let elevation = 0;
         while(!canFitIntoElevation(elevationTable,frame,elevation)) {elevation++;}
         fitIntoElevation(elevationTable, frame, elevation);
         elevationForEachFrame.push(elevation);
    }
    let visitedTokenCount = 0;
    for(const tokenCount of tokenCountForEachLine) {
        elevationsForEachLine.push(
            getElevationsWithinSpan(elevationTable, visitedTokenCount, visitedTokenCount+tokenCount));
        visitedTokenCount += tokenCount;
    }
    return {elevationForEachFrame, elevationsForEachLine};
}


function initElevationTable(tokenCount: number):boolean[][] {
    return [Array(tokenCount).fill(false)];
}


function canFitIntoElevation(elevationTable: boolean[][], frame: Frame, elevation: number): boolean {
    if (elevationTable.length <= elevation) {
        growElevationTableTo(elevationTable, elevation);
        return true;
    }
    if(frame.roles.length<=0) return true;
    const [beginTokenIndex, endTokenIndex] = Frame.getTokenSpan(frame);
    for (let iToken = beginTokenIndex; iToken < endTokenIndex; iToken++) {
        if (elevationTable[elevation][iToken]) {
            return false;
        }
    }
    return true;
}

// fit the frame into a given elevation. update elevation table and set the "elevation" field of the frame.
function fitIntoElevation(elevationTable: boolean[][], frame: Frame, elevation: number):void {
    if(frame.roles.length<=0) return;
    const [beginTokenIndex, endTokenIndex] = Frame.getTokenSpan(frame);
    for (let iToken = beginTokenIndex; iToken < endTokenIndex; iToken++) {
        elevationTable[elevation][iToken] = true;
    }
}

function growElevationTableTo(elevationTable: boolean[][], elevation:number) {
    while (elevationTable.length <= elevation) {
        const newRow = elevationTable[0].map(()=>false);
        elevationTable.push(newRow);
    }
}

// get the number of elevations within a span
function getElevationsWithinSpan(elevationTable:boolean[][], begin:number, end:number):number {
    let maxElevation = elevationTable.length - 1;
    for(let iElevation = maxElevation; iElevation>=0;iElevation--) {
        for(let iToken = begin; iToken<end; iToken++) {
            if(elevationTable[iElevation][iToken]) return iElevation+1;
        }
    }
    return 0;
}

export default calculateFrameElevation;