import { TextChannel, ThreadChannel } from 'discord.js'
import { Channel, UserMessage } from '../index.js'
import fs from 'fs/promises'
import path from 'path'

/**
 * Method to check if a thread history file exists
 * 
 * @param channel parent thread of the requested thread (can be GuildText)
 * @returns true if channel exists, false otherwise
 */
async function checkChannelInfoExists(channel: TextChannel, user: string) {
    const doesExists: boolean = await new Promise((resolve) => {
        getChannelInfo(`${channel.id}-${user}.json`, (channelInfo) => {
            if (channelInfo?.messages) {
                resolve(true)
            } else {
                resolve(false)
            }
        })
    })
    return doesExists
}

/**
 * Method to clear channel history for requesting user
 * 
 * @param filename guild id string
 * @param channel the TextChannel in the Guild
 * @param user username or ID of user
 * @returns true if history was cleared, false if already empty or not found
 */
export async function clearChannelInfo(filename: string, channel: TextChannel, user: string): Promise<boolean> {
    const channelInfoExists: boolean = await checkChannelInfoExists(channel, user)

    // If thread does not exist, file can't be found
    if (!channelInfoExists) return false

    // Attempt to clear user channel history
    const fullFileName = path.join('/app/data', `${filename}-${user}.json`)
    try {
        const data = await fs.readFile(fullFileName, 'utf8')
        const object = JSON.parse(data)
        if (object['messages'].length === 0) {
            console.log(`[Util: clearChannelInfo] History already empty for ${fullFileName}`)
            return false
        }
        object['messages'] = []
        await fs.writeFile(fullFileName, JSON.stringify(object, null, 2), { flag: 'w', mode: 0o600 })
        console.log(`[Util: clearChannelInfo] Cleared history for ${fullFileName}`)
        return true
    } catch (error) {
        console.log(`[Util: clearChannelInfo] Failed to clear ${fullFileName}: ${error}`)
        return false
    }
}

/**
 * Method to open the channel history
 * 
 * @param filename name of the json file for the channel by user (without path)
 * @param channel the text channel info
 * @param user the user's ID or clientId for bots
 * @param messages their messages
 */
export async function openChannelInfo(filename: string, channel: TextChannel | ThreadChannel, user: string, messages: UserMessage[] = []): Promise<void> {
    const fullFileName = path.join('/app/data', `${filename}-${user}.json`)
    console.log(`[Util: openChannelInfo] Attempting to create/open ${fullFileName}`)
    try {
        if (await fs.access(fullFileName).then(() => true).catch(() => false)) {
            const data = await fs.readFile(fullFileName, 'utf8')
            const object = JSON.parse(data)
            if (messages.length > 0) {
                object['messages'] = messages
            }
            await fs.writeFile(fullFileName, JSON.stringify(object, null, 2), { flag: 'w', mode: 0o600 })
            console.log(`[Util: openChannelInfo] Updated ${fullFileName}`)
        } else {
            const object: Channel = {
                id: channel?.id || filename,
                name: channel?.name || 'unknown',
                user,
                messages: messages
            }
            const directory = path.dirname(fullFileName)
            await fs.mkdir(directory, { recursive: true })
            await fs.writeFile(fullFileName, JSON.stringify(object, null, 2), { flag: 'w', mode: 0o600 })
            console.log(`[Util: openChannelInfo] Created '${fullFileName}' in working directory`)
        }
    } catch (error) {
        console.log(`[Util: openChannelInfo] Failed to write ${fullFileName}: ${error}`)
        throw error
    }
}

/**
 * Method to get the channel information/history
 * 
 * @param filename name of the json file for the channel by user (without path)
 * @param callback function to handle resolving message history
 */
export async function getChannelInfo(filename: string, callback: (config: Channel | undefined) => void): Promise<void> {
    const fullFileName = path.join('/app/data', filename)
    console.log(`[Util: getChannelInfo] Reading ${fullFileName}`)
    try {
        const data = await fs.readFile(fullFileName, 'utf8')
        const config = JSON.parse(data)
        if (!config || !Array.isArray(config.messages)) {
            console.log(`[Util: getChannelInfo] Invalid or empty config in ${fullFileName}: ${JSON.stringify(config)}`)
            callback(undefined)
        } else {
            console.log(`[Util: getChannelInfo] Successfully read ${fullFileName}`)
            callback(config)
        }
    } catch (error) {
        console.log(`[Util: getChannelInfo] Failed to read ${fullFileName}: ${error}`)
        callback(undefined)
    }
}