import Prompt from "inquirer/lib/prompts/base";
import observe from "inquirer/lib/utils/events";
import {Answers, MultiTextInputQuestion, Question} from "inquirer";
import {Interface as ReadLineInterface} from "readline";
import {filter} from "rxjs/operators"
import chalk from "chalk";
import {Subject} from "rxjs";
import figures from "figures";
import Paginator from "inquirer/lib/utils/paginator";

interface ExtendedReadLine extends ReadLineInterface {
    line: string
    cursor: number
}

declare module "inquirer" {
    export interface MultiTextInputQuestionOptions {
        pageSize?: number
    }

    export interface MultiTextInputQuestion<AnswerT extends Answers = Answers> extends Question<AnswerT>, MultiTextInputQuestionOptions {
        /** @inheritDoc */
        type: "multitext"
        default?: string[]
    }

    export interface QuestionMap {
        ["multitext"]: HierarchicalCheckboxQuestion
    }
}

export class MultiTextInput<AnswerT extends Answers = Answers, QuestionT extends MultiTextInputQuestion<AnswerT> = MultiTextInputQuestion> extends Prompt<QuestionT> {

    constructor(question: QuestionT, readline: ExtendedReadLine, answers: AnswerT) {
        super(question, readline, answers);
        this.value = question.default?.slice() || []
        this.activeIndex = this.value.length
    }

    _run(callback: MultiTextInput["done"]) {
        this.status = "touched"
        this.done = callback
        const events = observe(this.rl);
        this.rl.on("history", (history) => {
            history.splice(0, history.length)
        })
        events.normalizedUpKey.subscribe(() => this.onUpKey())
        events.normalizedDownKey.subscribe(() => this.onDownKey())
        events.line.subscribe((line) => this.onLine(line))
        events.keypress.pipe(filter((event) => {
            return event.key.name === "r" && event.key.ctrl === true
        })).subscribe(() => this.onReset())
        events.keypress.pipe(filter((event) => {
            return event.key.name === "x" && event.key.ctrl === true
        })).subscribe(() => this.onClear())
        events.keypress.subscribe(() => this.scheduleRender())
        const onSubmit = this.handleSubmitEvents(this.submitter)
        onSubmit.success.subscribe((result) => this.onValidated(result.value))
        onSubmit.error.subscribe((result) => this.onValidationError(result.isValid))
        this.scheduleRender()
    }

    private done: (state: any) => void|null
    private activeIndex: number
    private readonly value: string[]
    private submitter: Subject<string[]> = new Subject<string[]>()
    // @ts-ignore
    private paginator: Paginator = new Paginator(this.screen, {isInfinite: false});
    private scheduledRender: NodeJS.Immediate|null = null

    private get readline(): ExtendedReadLine {
        return this.rl
    }

    private get isNew(): boolean {
        return this.activeIndex === this.value.length
    }

    private get activeValue(): string {
        return this.isNew ? "" : this.value[this.activeIndex]
    }

    private set activeValue(newValue: string) {
        if (this.isNew) {
            this.value.push(newValue)
        } else {
            this.value[this.activeIndex] = newValue
        }
    }

    private render(error?: string) {
        this.scheduledRender = null
        const outputs: string[] = [this.getQuestion()]
        const bottomOutputs: string[] = []
        if (this.status === "answered") {
            outputs.push(...this.value.map((s) => chalk.cyan(`${s}`)).join(", "))
        } else {
            if (typeof error === "string") {
                bottomOutputs.push(`${figures.warning} ${error}`)
            } else if (this.readline.line === "") {
                if (this.isNew) {
                    bottomOutputs.push(chalk.dim(`Begin typing to add a new entry. Press ${chalk.yellow("<enter>")} to submit these entries, ${chalk.yellow("<ctrl>+x")} to delete all entries, or ${chalk.yellow("<up>")}/${chalk.yellow("<down>")} to change existing entries.`))
                } else {
                    bottomOutputs.push(chalk.dim(`Press ${chalk.yellow("<enter>")} or ${chalk.yellow("<ctrl>+x")} to delete this entry or ${chalk.yellow("<ctrl>+r")} to revert.`))
                }
            } else {
                outputs.push(this.readline.line)
                if (this.isNew) {
                    bottomOutputs.push(chalk.dim(`Press ${chalk.yellow("<enter>")} to add this entry or ${chalk.yellow("<ctrl>+r")} or ${chalk.yellow("<ctrl>+x")} to clear it.`))
                } else if (this.activeValue !== this.readline.line) {
                    bottomOutputs.push(chalk.dim(`Press ${chalk.yellow("<enter>")} to save this entry, ${chalk.yellow("<ctrl>+r")} to revert it, or ${chalk.yellow("<ctrl>+x")} to delete it.`))
                } else {
                    bottomOutputs.push(chalk.dim(`Begin typing to change this entry or press ${chalk.yellow("<ctrl>+x")} to delete it. Press ${chalk.yellow("<up>")}/${chalk.yellow("<down>")} to change other entries.`))
                }
            }
            bottomOutputs.push(this.renderList())
        }
        this.screen.render(outputs.join(""), bottomOutputs.join("\n"))
    }

    private renderList(): string {
        const outputs: string[] = []

        outputs.push(...this.value.map((entry, index):string => {
            const isSelected = index === this.activeIndex
            return `${isSelected ? chalk.cyan(figures.pointer) : " "} ${isSelected ? chalk.cyan(entry) : entry}`
        }))

        outputs.push(`${this.isNew ? chalk.cyan(figures.pointer) : " "} ${this.isNew ? chalk.cyan.dim("(New Entry)") : chalk.dim("(New Entry)")}`)

        // @ts-ignore
        return this.paginator.paginate(outputs.join("\n"), this.activeIndex, this.opt.pageSize)
    }

    private onUpKey() {
        if (this.readline.line !== this.activeValue) {
            return
        }
        if (this.activeIndex > 0) {
            this.changeIndex(-1)
            this.scheduleRender()
        }
    }

    private onDownKey() {
        if (this.readline.line !== this.activeValue) {
            return
        }
        if (this.activeIndex < this.value.length) {
            this.changeIndex(+1)
            this.scheduleRender()
        }
    }

    private onLine(line: string) {
        if (line === "") {
            if (this.isNew) {
                this.submitter.next(this.value.slice())
            } else {
                this.value.splice(this.activeIndex, 1)
                this.changeIndex(0)
            }
        } else {
            this.activeValue = line
            this.changeIndex(+1)
        }
        this.scheduleRender()
    }

    private onReset() {
        this.changeIndex(0)
        this.scheduleRender()
    }

    private onClear() {
        if (!this.isNew) {
            this.value.splice(this.activeIndex, 1)
            this.changeIndex(0)
            this.scheduleRender()
        } else if (this.readline.line !== "") {
            this.readline.line = ""
        } else {
            this.value.splice(0, this.value.length)
            this.activeIndex = 0
            this.changeIndex(0)
        }
        this.scheduleRender()
    }

    private scheduleRender() {
        if (this.scheduledRender === null) {
            this.scheduledRender = setImmediate(() => this.render())
        }
    }

    private changeIndex(by: number) {
        this.activeIndex += by
        if (this.activeIndex < 0) {
            this.activeIndex = 0
        } else if (this.activeIndex > this.value.length) {
            this.activeIndex = this.value.length
        }
        this.readline.line = this.activeValue
        this.readline.cursor = this.activeValue.length
    }

    private onValidationError(isValid: false|string) {
        this.render(typeof isValid === "string" ? chalk.red(isValid) : chalk.dim.red("Invalid input"))
    }

    private onValidated(value: string[]) {
        this.value.splice(0, this.value.length, ...value)
        this.status = "answered"
        this.render()
        this.screen.done()
        this.done(value)
    }
}