/**
 * This is responsible for creating the controls pane in the UI.
 */

import LocalStoreContext from '../runtime/ui/LocalStoreContext'

export interface ControlVariableConfig {
    label: string
    name: string
    default: LocalStoreValue
    tooltip?: string
    validation?: (value: LocalStoreValue) => {isValid: boolean, message: string}
    options?: {
        label: string
        value: LocalStoreValue
    }[]
}

export interface ControlVariable extends ControlVariableConfig {
    type: 'number'|'string'|'boolean'
}

type LocalStoreValue = string | number | boolean

export interface ControlsConstructor {
    root: HTMLDivElement
    settings: ControlVariableConfig[]
    id?: string
    title?: string
}

export default class Controls {
    private context: LocalStoreContext
    private settings: ControlVariable[] = []

    constructor(opts: ControlsConstructor) {
        const { root, settings, title = 'Controls', id = '_controls_' } = opts

        this.context = new LocalStoreContext(id)

        // infer a type for each setting
        settings.forEach( setting => {
            if (typeof setting.default === 'string') {
                // setting.type = 'string'
                this.settings.push({type: 'string', ...setting})
            } else if (typeof setting.default === 'number') {
                // setting.type = 'number'
                this.settings.push({type: 'number', ...setting})
            } else if (typeof setting.default === 'boolean') {
                // setting.type = 'boolean'
                this.settings.push({type: 'boolean', ...setting})
            } else {
                throw new Error(`Unknown type for setting ${setting.name}`)
            }
        })

        if (this.context.length() === 0) {
            this.settings.forEach( setting => {
                this.context.set(setting.name, setting.default, setting.type)
            })
        }

        const controlsPane = document.createElement('drag-pane')
        controlsPane.setAttribute('heading', title)
        controlsPane.setAttribute('key', 'controls')

        const controlsContainer = document.createElement('div')
        controlsContainer.style.display = 'flex'
        controlsContainer.style.flexDirection = 'column'
        controlsContainer.style.alignItems = 'flex-start'
        controlsContainer.style.padding = '5px'
        controlsContainer.style.width = 300 + 'px'

        const resetButton = document.createElement('button')
        resetButton.innerText = 'Reset Values'
        resetButton.style.margin = '5px'
        resetButton.addEventListener('click', () => {
            this.reset()
            window.location.reload()
        })

        this.settings.forEach(setting => {
            const control = setting?.options && setting.options.length > 0
                ? generateSelection(setting, this.context)    
                : generateInput(setting, this.context)
            controlsContainer.appendChild(control)
        })

        controlsContainer.appendChild(resetButton)
        controlsPane.appendChild(controlsContainer)
        root.appendChild(controlsPane)
    }

    public getSetting(name: string) {
        return this.context.get(name)
    }

    public setSetting(name: string, value: LocalStoreValue, type: ControlVariable['type']): void {
        this.context.set(name, value, type)
    }

    public reset(): void {
        this.context.clear()
        this.settings.forEach( setting => {
            this.context.set(setting.name, setting.default, setting.type)
        })
    }
}

// generates select & option elements based on the options of the setting
const generateSelection = (setting: ControlVariable, context: LocalStoreContext): HTMLDivElement => {
    // create a div to hold the input and label
    const wrapper = document.createElement('div')

    const select = document.createElement('select')
    select.style.margin = '1px 3px'
    select.style.width = '200px'

    setting.options?.forEach( option => {
        const optionElement = document.createElement('option')
        optionElement.value = option.value as string
        optionElement.innerText = option.label as string
        select.appendChild(optionElement)
    })

    select.value = context.get(setting.name) as string

    select.id = setting.name

    const label = document.createElement('label')
    label.htmlFor = setting.name
    label.innerText = setting.label
    label.title = setting.tooltip || ''

    // underline the label if it has a tooltip
    if (setting.tooltip) {
        label.style.cursor = 'help'
    }

    wrapper.appendChild(label)
    wrapper.appendChild(select)

    wrapper.querySelector('select')!.addEventListener('input', (event) => {
        context.set(setting.name, (event.target as HTMLSelectElement).value, setting.type)
    })

    return wrapper
}

// generates an input element based on the type of the setting
const generateInput = (setting: ControlVariable, context: LocalStoreContext): HTMLDivElement => {
    // create a div to hold the input and label
    const wrapper = document.createElement('div')

    const input = document.createElement('input')
    input.style.margin = '1px 3px'
    input.style.width = '50px'

    // counts the number of decimal places in a float
    const numericalPrecision = typeof context.get(setting.name) === 'number'
        ? ((context.get(setting.name) as number).toString().split('.')[1] ?? []).length
        : null

    switch(setting.type) {
    case 'number':
        input.type = 'number'
        input.value = context.get(setting.name) as string
        if (numericalPrecision) {
            input.step = '0.' + '0'.repeat(numericalPrecision - 1) + '1'
        } else {
            input.step = '1'
        }
        break
    case 'string':
        input.type = 'text'
        input.value = context.get(setting.name) as string
        break
    case 'boolean':
        input.type = 'checkbox'
        input.checked = context.get(setting.name) as boolean
        break
    }

    input.id = setting.name

    const label = document.createElement('label')
    label.htmlFor = setting.name
    label.innerText = setting.label
    label.title = setting.tooltip || ''

    // underline the label if it has a tooltip
    if (setting.tooltip) {
        label.style.cursor = 'help'
    }

    wrapper.appendChild(label)
    wrapper.appendChild(input)

    wrapper.querySelector('input')!.addEventListener('input', (event) => {

        let newValue: LocalStoreValue
        let oldValue = context.get(setting.name)

        if ( setting.type === 'boolean' ) {
            newValue = (event.target as HTMLInputElement).checked
        } else {
            newValue = (event.target as HTMLInputElement).value
        }
        
        if (setting.validation) {
            const {isValid = true, message = ''} = setting.validation(newValue) ?? {}
            if (!isValid) {
                console.error(`Invalid value for ${setting.name}: ${message}`)
                context.set(setting.name, oldValue, setting.type)
                ;(event.target as HTMLInputElement).value = oldValue as string
            } else {
                context.set(setting.name, newValue, setting.type)
            }
        } else {
            context.set(setting.name, newValue, setting.type)
        }

    })

    return wrapper
}