const constants = require("./constants")
const {request} = require("./utils/request")
const switcher = require("./utils/torswitcher")
const {extractSharedData} = require("./utils/body")
const {TtlCache, RequestCache} = require("./cache")
const RequestHistory = require("./structures/RequestHistory")
const db = require("./db")
require("./testimports")(constants, request, extractSharedData, RequestCache, RequestHistory)

const requestCache = new RequestCache(constants.caching.resource_cache_time)
/** @type {import("./cache").TtlCache<import("./structures/TimelineEntry")>} */
const timelineEntryCache = new TtlCache(constants.caching.resource_cache_time)
const history = new RequestHistory(["user", "timeline", "post", "reel"])

async function fetchUser(username) {
	if (constants.allow_user_from_reel === "never") {
		return fetchUserFromHTML(username)
	} else if (constants.allow_user_from_reel === "prefer") {
		const userID = db.prepare("SELECT user_id FROM Users WHERE username = ?").pluck().get(username)
		if (userID) return fetchUserFromCombined(userID, username)
		else return fetchUserFromHTML(username)
	} else { // === "fallback"
		return fetchUserFromHTML(username).catch(error => {
			if (error === constants.symbols.INSTAGRAM_DEMANDS_LOGIN || error === constants.symbols.RATE_LIMITED) {
				const userID = db.prepare("SELECT user_id FROM Users WHERE username = ?").pluck().get(username)
				if (userID) return fetchUserFromCombined(userID, username)
			}
			throw error
		})
	}
}

function fetchUserFromHTML(username) {
	return requestCache.getOrFetch("user/"+username, () => {
		return switcher.request("user_html", `https://www.instagram.com/${username}/`, async res => {
			if (res.status === 302) throw constants.symbols.INSTAGRAM_DEMANDS_LOGIN
			if (res.status === 429) throw constants.symbols.RATE_LIMITED
			return res
		}).then(res => {
			if (res.status === 404) {
				throw constants.symbols.NOT_FOUND
			} else {
				return res.text().then(text => {
					// require down here or have to deal with require loop. require cache will take care of it anyway.
					// User -> Timeline -> TimelineEntry -> collectors -/> User
					const User = require("./structures/User")
					const sharedData = extractSharedData(text)
					const user = new User(sharedData.entry_data.ProfilePage[0].graphql.user)
					history.report("user", true)
					if (constants.caching.db_user_id) {
						db.prepare("INSERT OR IGNORE INTO Users (username, user_id) VALUES (@username, @user_id)")
							.run({username: user.data.username, user_id: user.data.id})
					}
					return user
				})
			}
		}).catch(error => {
			if (error === constants.symbols.INSTAGRAM_DEMANDS_LOGIN || error === constants.symbols.RATE_LIMITED) {
				history.report("user", false)
			}
			throw error
		})
	})
}

function fetchUserFromCombined(userID, username) {
	// Fetch basic user information
	const p = new URLSearchParams()
	p.set("query_hash", constants.external.reel_query_hash)
	p.set("variables", JSON.stringify({
		user_id: userID,
		include_reel: true
	}))
	return requestCache.getOrFetch("user/"+username, () => {
		return switcher.request("reel_graphql", `https://www.instagram.com/graphql/query/?${p.toString()}`, async res => {
			if (res.status === 429) throw constants.symbols.RATE_LIMITED
			return res
		}).then(res => res.json()).then(root => {
			const result = root.data.user
			if (!result) throw constants.symbols.NOT_FOUND
			// require down here or have to deal with require loop. require cache will take care of it anyway.
			// ReelUser -> Timeline -> TimelineEntry -> collectors -/> User
			const ReelUser = require("./structures/ReelUser")
			const user = new ReelUser(result.reel.user)
			return user
		}).catch(error => {
			throw error
		})
	}).then(async user => {
		// Add first timeline page
		if (!user.timeline.pages[0]) {
			const page = await fetchTimelinePage(userID, "")
			user.timeline.addPage(page)
		}
		history.report("reel", true)
		return user
	}).catch(error => {
		if (error === constants.symbols.RATE_LIMITED) {
			history.report("reel", false)
		}
		throw error
	})
}

/**
 * @param {string} userID
 * @param {string} after
 * @returns {Promise<import("./types").PagedEdges<import("./types").TimelineEntryN2>>}
 */
function fetchTimelinePage(userID, after) {
	const p = new URLSearchParams()
	p.set("query_hash", constants.external.timeline_query_hash)
	p.set("variables", JSON.stringify({
		id: userID,
		first: constants.external.timeline_fetch_first,
		after: after
	}))
	return requestCache.getOrFetchPromise(`page/${userID}/${after}`, () => {
		return switcher.request("timeline_graphql", `https://www.instagram.com/graphql/query/?${p.toString()}`, async res => {
			if (res.status === 429) throw constants.symbols.RATE_LIMITED
			return res
		}).then(res => res.json()).then(root => {
			/** @type {import("./types").PagedEdges<import("./types").TimelineEntryN2>} */
			const timeline = root.data.user.edge_owner_to_timeline_media
			history.report("timeline", true)
			return timeline
		}).catch(error => {
			if (error === constants.symbols.RATE_LIMITED) {
				history.report("timeline", false)
			}
			throw error
		})
	})
}

/**
 * @param {string} shortcode
 * @returns {import("./structures/TimelineEntry")}
 */
function getOrCreateShortcode(shortcode) {
	if (timelineEntryCache.has(shortcode)) {
		return timelineEntryCache.get(shortcode)
	} else {
		// require down here or have to deal with require loop. require cache will take care of it anyway.
		// TimelineEntry -> collectors -/> TimelineEntry
		const TimelineEntry = require("./structures/TimelineEntry")
		const result = new TimelineEntry()
		timelineEntryCache.set(shortcode, result)
		return result
	}
}

async function getOrFetchShortcode(shortcode) {
	if (timelineEntryCache.has(shortcode)) {
		return timelineEntryCache.get(shortcode)
	} else {
		const data = await fetchShortcodeData(shortcode)
		const entry = getOrCreateShortcode(shortcode)
		entry.applyN3(data)
		return entry
	}
}

/**
 * @param {string} shortcode
 * @returns {Promise<import("./types").TimelineEntryN3>}
 */
function fetchShortcodeData(shortcode) {
	// example actual query from web:
	// query_hash=2b0673e0dc4580674a88d426fe00ea90&variables={"shortcode":"xxxxxxxxxxx","child_comment_count":3,"fetch_comment_count":40,"parent_comment_count":24,"has_threaded_comments":true}
	// we will not include params about comments, which means we will not receive comments, but everything else should still work fine
	const p = new URLSearchParams()
	p.set("query_hash", constants.external.shortcode_query_hash)
	p.set("variables", JSON.stringify({shortcode}))
	return requestCache.getOrFetchPromise("shortcode/"+shortcode, () => {
		return switcher.request("post_graphql", `https://www.instagram.com/graphql/query/?${p.toString()}`, async res => {
			if (res.status === 429) throw constants.symbols.RATE_LIMITED
			return res
		}).then(res => res.json()).then(root => {
			/** @type {import("./types").TimelineEntryN3} */
			const data = root.data.shortcode_media
			if (data == null) {
				// the thing doesn't exist
				throw constants.symbols.NOT_FOUND
			} else {
				history.report("post", true)
				if (constants.caching.db_post_n3) {
					db.prepare("REPLACE INTO Posts (shortcode, id, id_as_numeric, username, json) VALUES (@shortcode, @id, @id_as_numeric, @username, @json)")
						.run({shortcode: data.shortcode, id: data.id, id_as_numeric: data.id, username: data.owner.username, json: JSON.stringify(data)})
				}
				// if we have the owner but only a reelUser, update it. this code is gross.
				if (requestCache.hasNotPromise("user/"+data.owner.username)) {
					const user = requestCache.getWithoutClean("user/"+data.owner.username)
					if (user.fromReel) {
						user.data.full_name = data.owner.full_name
						user.data.is_verified = data.owner.is_verified
					}
				}
				return data
			}
		}).catch(error => {
			if (error === constants.symbols.RATE_LIMITED) {
				history.report("post", false)
			}
			throw error
		})
	})
}

module.exports.fetchUser = fetchUser
module.exports.fetchTimelinePage = fetchTimelinePage
module.exports.getOrCreateShortcode = getOrCreateShortcode
module.exports.fetchShortcodeData = fetchShortcodeData
module.exports.requestCache = requestCache
module.exports.timelineEntryCache = timelineEntryCache
module.exports.getOrFetchShortcode = getOrFetchShortcode
module.exports.history = history