/**
 * Copyright (c) 2019 mol* contributors, licensed under MIT, See LICENSE file for more info.
 *
 * @author Alexander Rose <alexander.rose@weirdbyte.de>
 */

import { ReaderResult as Result } from '../result'
import { Task, RuntimeContext } from 'mol-task'
import { PlyFile, PlyType, PlyElement } from './schema';
import { Tokenizer, TokenBuilder, Tokens } from '../common/text/tokenizer';
import { Column } from 'mol-data/db';
import { TokenColumn } from '../common/text/column/token';

interface State {
    data: string
    tokenizer: Tokenizer
    runtimeCtx: RuntimeContext

    comments: string[]
    elementSpecs: ElementSpec[]
    elements: PlyElement[]
}

function State(data: string, runtimeCtx: RuntimeContext): State {
    const tokenizer = Tokenizer(data)
    return {
        data,
        tokenizer,
        runtimeCtx,

        comments: [],
        elementSpecs: [],
        elements: []
    }
}

type ColumnProperty = { kind: 'column', type: PlyType, name: string }
type ListProperty = { kind: 'list', countType: PlyType, dataType: PlyType, name: string }
type Property = ColumnProperty | ListProperty

type TableElementSpec = { kind: 'table', name: string, count: number, properties: ColumnProperty[] }
type ListElementSpec = { kind: 'list', name: string, count: number, property: ListProperty }
type ElementSpec = TableElementSpec | ListElementSpec

function markHeader(tokenizer: Tokenizer) {
    const endHeaderIndex = tokenizer.data.indexOf('end_header', tokenizer.position)
    if (endHeaderIndex === -1) throw new Error(`no 'end_header' record found`)
    // TODO set `tokenizer.lineNumber` correctly
    tokenizer.tokenStart = tokenizer.position
    tokenizer.tokenEnd = endHeaderIndex
    tokenizer.position = endHeaderIndex
    Tokenizer.eatLine(tokenizer)
}

function parseHeader(state: State) {
    const { tokenizer, comments, elementSpecs } = state

    markHeader(tokenizer)
    const headerLines = Tokenizer.getTokenString(tokenizer).split(/\r?\n/)

    if (headerLines[0] !== 'ply') throw new Error(`data not starting with 'ply'`)
    if (headerLines[1] !== 'format ascii 1.0') throw new Error(`format not 'ascii 1.0'`)

    let currentName: string | undefined
    let currentCount: number | undefined
    let currentProperties: Property[] | undefined


    function addCurrentElementSchema() {
        if (currentName !== undefined && currentCount !== undefined && currentProperties !== undefined) {
            let isList = false
            for (let i = 0, il = currentProperties.length; i < il; ++i) {
                const p = currentProperties[i]
                if (p.kind === 'list') {
                    isList = true
                    break
                }
            }
            if (isList && currentProperties.length !== 1) throw new Error('expected single list property')
            if (isList) {
                elementSpecs.push({
                    kind: 'list',
                    name: currentName,
                    count: currentCount,
                    property: currentProperties[0] as ListProperty
                })
            } else {
                elementSpecs.push({
                    kind: 'table',
                    name: currentName,
                    count: currentCount,
                    properties: currentProperties as ColumnProperty[]
                })
            }
        }
    }

    for (let i = 2, il = headerLines.length; i < il; ++i) {
        const l = headerLines[i]
        const ls = l.split(' ')
        if (l.startsWith('comment')) {
            comments.push(l.substr(8))
        } else if (l.startsWith('element')) {
            addCurrentElementSchema()
            currentProperties = []
            currentName = ls[1]
            currentCount = parseInt(ls[2])
        } else if (l.startsWith('property')) {
            if (currentProperties === undefined) throw new Error(`properties outside of element`)
            if (ls[1] === 'list') {
                currentProperties.push({
                    kind: 'list',
                    countType: PlyType(ls[2]),
                    dataType: PlyType(ls[3]),
                    name: ls[4]
                })
            } else {
                currentProperties.push({
                    kind: 'column',
                    type: PlyType(ls[1]),
                    name: ls[2]
                })
            }
        } else if (l.startsWith('end_header')) {
            addCurrentElementSchema()
        } else {
            console.warn('unknown header line')
        }
    }
}

function parseElements(state: State) {
    const { elementSpecs } = state
    for (let i = 0, il = elementSpecs.length; i < il; ++i) {
        const spec = elementSpecs[i]
        if (spec.kind === 'table') parseTableElement(state, spec)
        else if (spec.kind === 'list') parseListElement(state, spec)
    }
}

function getColumnSchema(type: PlyType): Column.Schema {
    switch (type) {
        case 'char': case 'uchar': case 'int8': case 'uint8':
        case 'short': case 'ushort': case 'int16': case 'uint16':
        case 'int': case 'uint': case 'int32': case 'uint32':
            return Column.Schema.int
        case 'float': case 'double': case 'float32': case 'float64':
            return Column.Schema.float
    }
}

function parseTableElement(state: State, spec: TableElementSpec) {
    const { elements, tokenizer } = state
    const { count, properties } = spec
    const propertyCount = properties.length
    const propertyNames: string[] = []
    const propertyTypes: PlyType[] = []
    const propertyTokens: Tokens[] = []
    const propertyColumns = new Map<string, Column<number>>()

    for (let i = 0, il = propertyCount; i < il; ++i) {
        const tokens = TokenBuilder.create(tokenizer.data, count * 2)
        propertyTokens.push(tokens)
    }

    for (let i = 0, il = count; i < il; ++i) {
        for (let j = 0, jl = propertyCount; j < jl; ++j) {
            Tokenizer.skipWhitespace(tokenizer)
            Tokenizer.markStart(tokenizer)
            Tokenizer.eatValue(tokenizer)
            TokenBuilder.addUnchecked(propertyTokens[j], tokenizer.tokenStart, tokenizer.tokenEnd)
        }
    }

    for (let i = 0, il = propertyCount; i < il; ++i) {
        const { type, name } = properties[i]
        const column = TokenColumn(propertyTokens[i], getColumnSchema(type))
        propertyNames.push(name)
        propertyTypes.push(type)
        propertyColumns.set(name, column)
    }

    elements.push({
        kind: 'table',
        rowCount: count,
        propertyNames,
        propertyTypes,
        getProperty: (name: string) => propertyColumns.get(name)
    })
}

function parseListElement(state: State, spec: ListElementSpec) {
    const { elements, tokenizer } = state
    const { count, property } = spec

    // initial tokens size assumes triangle index data
    const tokens = TokenBuilder.create(tokenizer.data, count * 2 * 3)

    const offsets = new Uint32Array(count + 1)
    let entryCount = 0

    for (let i = 0, il = count; i < il; ++i) {
        // skip over row entry count as it is determined by line break
        Tokenizer.skipWhitespace(tokenizer)
        Tokenizer.eatValue(tokenizer)

        while (Tokenizer.skipWhitespace(tokenizer) !== 10) {
            ++entryCount
            Tokenizer.markStart(tokenizer)
            Tokenizer.eatValue(tokenizer)
            TokenBuilder.addToken(tokens, tokenizer)
        }
        offsets[i + 1] = entryCount
    }

    // console.log(tokens.indices)
    // console.log(offsets)

    /** holds row value entries transiently */
    const listValue = {
        entries: [] as number[],
        count: 0
    }

    const column = TokenColumn(tokens, getColumnSchema(property.dataType))

    elements.push({
        kind: 'list',
        rowCount: count,
        name: property.name,
        type: property.dataType,
        value: (row: number) => {
            const start = offsets[row]
            const end = offsets[row + 1]
            for (let i = start; i < end; ++i) {
                listValue.entries[i - start] = column.value(i)
            }
            listValue.count = end - start
            return listValue
        }
    })
}

async function parseInternal(data: string, ctx: RuntimeContext): Promise<Result<PlyFile>> {
    const state = State(data, ctx);
    ctx.update({ message: 'Parsing...', current: 0, max: data.length });
    parseHeader(state)
    // console.log(state.comments)
    // console.log(JSON.stringify(state.elementSpecs, undefined, 4))
    parseElements(state)
    const { elements, elementSpecs, comments } = state
    const elementNames = elementSpecs.map(s => s.name)
    const result = PlyFile(elements, elementNames, comments)
    return Result.success(result);
}

export function parse(data: string) {
    return Task.create<Result<PlyFile>>('Parse PLY', async ctx => {
        return await parseInternal(data, ctx)
    })
}

export default parse;