#!/bin/sh
# shellcheck disable=SC2236,SC2237
#
# ^ Allow the use of `! -z` and `! [ -z]` as those are
# more intuitive than `-n`


#
# Globals
#

ALL_CLIENTS="web
web-embed
web-mobile
android
android-embed
apple-ios
tv-html5
tv-html5-embed"


#
# Utility functions
#

print_usage()
{
	(
		echo "Usage: yt-api-helper  -i [-c <client>] [-e <endpoint>]"
		echo "Usage: yt-api-helper  -c <client> -e <endpoint> -d <data>"
	) >&2
}

print_help()
{
	print_usage

	(
		echo ""
		echo "Options:"
		echo "  -c,--client       Client to use. Mandatory in non-interactive mode."
		echo "  -d,--data         Raw data to send to the API"
		echo "  -e,--endpoint     Youtube endpoint to request."
		echo "                      Mandatory in non-interactive mode"
		echo "  -h,--help         Show this help"
		echo "  -i,--interactive  Run in interactive mode"
		echo "  -o,--output       Print output to file instead of stdout"
		echo ""
		echo "     --debug        Show what is sent to the API"
		echo ""
	) >&2

	print_clients
	print_endpoints
}

print_clients()
{
	(
		echo ""
		echo "Available clients:"

		for client in $ALL_CLIENTS; do
			echo " - $client"
		done
	) >&2
}

print_endpoints()
{
	(
		echo ""
		echo "Available endpoints:"
		echo " - browse"
		echo " - browse-continuation"
		echo " - next"
		echo " - next-continuation"
		echo " - player"
		echo " - search"
		echo " - resolve"
	) >&2
}


query_with_default()
{
	prompt="$1"
	default="$2"

	printf "%s [%s]: " "$prompt" "$default" >&2
	read -r data

	if [ -z "$data" ]; then
		echo "$default"
	else
		echo "$data"
	fi
}

query_with_error()
{
	prompt="$1"
	error_message="$2"

	printf "%s []: " "$prompt" >&2
	read -r data

	if [ -z "$data" ]; then
		error_msg "$error_message"
		exit 1
	else
		echo "$data"
	fi
}


is_arg()
{
	case $1 in
		-c|--client)      true;;
		-d|--data)        true;;
		-e|--endpoint)    true;;
		-h|--help)        true;;
		-i|--interactive) true;;
		-o|--output)      true;;
		--debug)          true;;
		*)                false;;
	esac
}


error_msg()
{
	printf "Error: %s\n" "$1" >&2
}


#
# Client selection function
#

client_select()
{
	# Default API key, used by most clients
	apikey="AIzaSyAO_FJ2SlqU8Q4STEHLGCilw_Y9_11qcW8"

	# Default user-agent
	user_agent="Mozilla/5.0 (Windows NT 10.0; rv:78.0) Gecko/20100101 Firefox/78.0"

	# Reset values, in case this function is used multiple times
	client_name=""
	client_vers=""

	client_extra_device_make=""
	client_extra_device_model=""
	client_extra_os_name=""
	client_extra_os_vers=""
	client_extra_platform=""
	client_extra_form_factor=""


	case "$1" in
		web)
			client_name="WEB"
			client_vers="2.20230217.01.00"
		;;

		web-embed)
			client_name="WEB_EMBEDDED_PLAYER"
			client_vers="1.20230217.01.0"
		;;

		web-mobile)
			client_name="MWEB"
			client_vers="2.20230216.06.00"
		;;

		android)
			apikey="AIzaSyA8eiZmM1FaDVjRy-df2KTyQ_vz_yYM39w"
			client_name="ANDROID"
			client_vers="17.31.35"
		;;

		android-embed)
			client_name="ANDROID_EMBEDDED_PLAYER"
			client_vers="17.31.35"
		;;

		apple-ios)
			apikey="AIzaSyB-63vPrdThhKuerbB2N_l7Kwwcxj6yUAc"
			client_name="IOS"
			client_vers="17.31.4"

			client_extra_device_make="Apple"
			client_extra_device_model="iPhone11,8"
			client_extra_os_vers="15.2.0"

			user_agent="com.google.ios.youtube/17.31.4 (iPhone11,8; U; CPU iOS 15_2 like Mac OS X; en_GB)"
		;;

		tv-html5)
			client_name="TVHTML5"
			client_vers="7.20220325"
		;;

		tv-html5-embed)
			client_name="TVHTML5_SIMPLY_EMBEDDED_PLAYER"
			client_vers="2.0"
			screen="EMBED"
		;;

		*)
			error_msg "Unknown client '$client_option'"
			print_clients
			exit 1
		;;
	esac
}


#
# Endpoint selection function
#

endpoint_select()
{
	case "$1" in
		browse)
			endpoint="youtubei/v1/browse"

			if [ $interactive = true ]; then
				browse_id=$(query_with_default "Enter browse ID" "UCXuqSBlHAE6Xw-yeJA0Tunw")
				endpoint_data="\"browseId\":\"${browse_id}\""
			fi
		;;

		browse-cont*|browse-tok*)
			endpoint="youtubei/v1/browse"

			if [ $interactive = true ]; then
				token=$(query_with_error "Enter continuation token" "token required")
				endpoint_data="\"continuation\":\"${token}\""
			fi
		;;

		player|next)
			endpoint="youtubei/v1/$endpoint_option"

			if [ $interactive = true ]; then
				vid=$(query_with_default "Enter video ID" "dQw4w9WgXcQ")
				endpoint_data="\"videoId\":\"${vid}\""

			fi
		;;

		next-cont*|next-tok*)
			endpoint="youtubei/v1/next"

			if [ $interactive = true ]; then
				token=$(query_with_error "Enter continuation token" "token required")
				endpoint_data="\"continuation\":\"${token}\""
			fi
		;;

		search)
			endpoint="youtubei/v1/search"

			if [ $interactive = true ]; then
				# Get search query, and escape backslashes and double quotes
				query=$(
					query_with_error "Enter your search query" "search term required" |
					sed -e 's/\\/\\\\/g' -e 's/"/\\"/g'
				)
				endpoint_data="\"query\":\"${query}\""
			fi
		;;

		resolve)
			endpoint="youtubei/v1/navigation/resolve_url"

			if [ $interactive = true ]; then
				url=$(query_with_error "Enter URL" "URL required")
				endpoint_data="\"url\":\"${url}\""
			fi
		;;

		*)
			error_msg "Unknown endpoint '$1'"
			print_endpoints
			exit 1
		;;
	esac


	# Interactively request additional parameters for the supported endpoints
	if [ $interactive = true ]
	then
		case "$1" in

		browse|player|search)
			params=$(query_with_default "Enter optional parameters (base64-encoded protobuf)" "")

			if [ ! -z "$params" ]; then
				endpoint_data="${endpoint_data},\"params\":\"${params}\""
			fi
		;;
		esac
	fi
}


#
# Function to craft the client data
#

make_request_data()
{
	client="\"hl\":\"${hl}\",\"gl\":\"${gl}\""

	client="${client},\"deviceMake\":\"${client_extra_device_make}\""
	client="${client},\"deviceModel\":\"${client_extra_device_model}\""

	if ! [ -z "$screen" ]; then
		client="${client},\"clientScreen\":\"${screen}\""
	fi

	client="${client},\"clientName\":\"${client_name}\""
	client="${client},\"clientVersion\":\"${client_vers}\""

	if ! [ -z "$client_extra_os_name" ]; then
		client="${client},\"osName\":\"${client_extra_os_name}\""
	fi

	if ! [ -z "$client_extra_os_vers" ]; then
		client="${client},\"osVersion\":\"${client_extra_os_vers}\""
	fi

	if ! [ -z "$client_extra_platform" ]; then
		client="${client},\"platform\":\"${client_extra_platform}\""
	fi

	if ! [ -z "$client_extra_form_factor" ]; then
		client="${client},\"clientFormFactor\":\"${client_extra_form_factor}\""
	fi


	data="{\"context\":{\"client\":{$client}},$endpoint_data}"

	# Basic debug
	if [ $debug = true ]; then
		if command -v jq >&2 >/dev/null; then
			printf "\nSending: %s\n\n" "$data" | jq . >&2
		else
			printf "\nSending: %s\n\n" "$data" | sed 's/{/{\n/g; s/}/\n}/g; s/,/,\n/g' >&2
		fi
	fi

	# Return data
	printf "{\"context\":{\"client\":{%s}},%s}\n" "$client" "$endpoint_data"
}


#
# Final command - send request to Youtube
#

send_request()
{
	request_data="$1"
	output_file="$2"

	url="https://www.youtube.com/${endpoint}?key=${apikey}"

	# Headers
	hdr_ct='Content-Type: application/json; charset=utf-8'
	hdr_ua="User-Agent: ${user_agent}"

	# Run!
	temp_dl=_curl_$(date '+%s')

	curl --compressed -H "$hdr_ct" -H "$hdr_ua" --data "$request_data" "$url" | \
	sed -E '
		/^\s+"(clickT|t)rackingParams.+,$/d
		s/,?\n\s+"(clickT|t)rackingParams.+$//
	' > "$temp_dl"

	# Print to STDOUT if no output file was given
	if [ -z "$output_file" ]; then
		cat "$temp_dl"
		rm "$temp_dl"
	else
		mv -- "$temp_dl" "$output_file"
	fi
}


#
# Parameters init
#

interactive=false
debug=false

client_option=""
endpoint_option=""

data=""


#
# Parse arguments
#

while :; do
	# Exit if no more arguments to parse
	if [ $# -eq 0 ]; then break; fi

	case $1 in
		-c|--client)
			shift

			if [ $# -eq 0 ] || is_arg "$1"; then
				error_msg "missing argument after -c/--client"
				print_usage
				exit 2
			fi

			client_option=$1
		;;

		-d|--data)
			shift

			if [ $# -eq 0 ] || is_arg "$1"; then
				error_msg "missing argument after -d/--data"
				print_usage
				exit 2
			fi

			data=$1
		;;

		-e|--endpoint)
			shift

			if [ $# -eq 0 ] || is_arg "$1"; then
				error_msg "missing argument after -e/--endpoint"
				print_usage
				exit 2
			fi

			endpoint_option=$1
		;;

		-h|--help)
			print_help
			exit 0
		;;

		-i|--interactive)
			interactive=true
		;;

		-o|--output)
			shift

			if [ $# -eq 0 ] || is_arg "$1"; then
				error_msg "missing argument after -o/--output"
				print_usage
				exit 2
			fi

			output="$1"
		;;

		--debug)
			debug=true
		;;

		*)
			error_msg "unknown argument '$1'"
			print_usage
			exit 2
		;;
	esac

	shift
done


#
# Input validation
#

if [ ! -z "$data" ]; then
	# Can't pass data in interactive mode
	if [ $interactive = true ]; then
		error_msg "-d/--data can't be used with -i/--interactive"
		print_usage
		exit 2
	fi

	# In non-interactive mode, we still need to pass a client
	# so the right API key is passed as a URL parameter
	if [ -z "$client_option" ]; then
		error_msg "-c/--client is required to select an API key"
		print_usage
		exit 2
	fi

	# Endpoint must be given if non-interactive mode
	if [ -z "$endpoint_option" ]; then
		error_msg "In non-interactive mode, an endpoint must be passed with -e/--endpoint"
		print_usage
		exit 2
	fi
fi

if [ -z "$data" ] && [ $interactive = false ]; then
	# Data must be given if non-interactive mode
	error_msg "In non-interactive mode, data must be passed with -d/--data"
	print_usage
	exit 2
fi

if [ -z "$output" ] && [ $interactive = true ]; then
	confirm=$(query_with_default "\nIt's recommended to use --output in interactive mode.\nContinue?" "No")

	case $confirm in
		[Yy]|[Yy][Ee][Ss]) ;;
		*) exit 0;;
	esac
fi


#
# Required parameters. Ask if not provided
#

if [ -z "$client_option" ]; then
	if [ $interactive = true ]; then
		print_clients
		client_option=$(query_with_default "\nEnter a client to use" "web")
	else
		exit 2
	fi
fi

if [ -z "$endpoint_option" ]; then
	if [ $interactive = true ]; then
		print_endpoints
		endpoint_option=$(query_with_default "\nEnter an endpoint to request" "")
	else
		exit 2
	fi
fi

# new line
echo >&2

# Interactive language/region selection
if [ $interactive = true ]; then
	hl=$(query_with_default "Enter content language (hl)" "en")
	gl=$(query_with_default "Enter content region (gl)"   "US")
fi


#
# Run the request
#

# Only ran once (this requests some additional data in interactive mode)
endpoint_select "$endpoint_option"

if [ "$client_option" = "all" ]; then
	# Run the client selector (get client-specific infos) and request for each client
	if [ -z "$output" ]; then
		printf "\nAll clients requested, response will be written to output file anyway\n" >&2
		output=response-$endpoint_option.$(date '+%s')
	else
		output=$(basename "$output" ".json")
	fi

	for client_name in $ALL_CLIENTS; do
		client_select "$client_name"

		if [ $interactive = true ]; then
			data=$(make_request_data)
		fi

		send_request "$data" "$output.$client_name.json"
	done
else
	# Run the client selection and request only once
	client_select "$client_option"

	if [ $interactive = true ]; then
		data=$(make_request_data);
	fi

	send_request "$data" "$output"
fi