#!/usr/bin/env bash

# START
set -e

# VARIABLES
#URL_DNS_LIST="https://pgl.yoyo.org/adservers/serverlist.php?showintro=0&mimetype=plaintext"
URL_DNS_LIST="https://raw.githubusercontent.com/StevenBlack/hosts/master/hosts"
NAME_OSX="Darwin"
THIS_OS=$(uname -mrs)
PROGNAME=$(basename "$0")
[[ -z "${XDG_CONFIG_HOME}" ]] && CONFIG=$HOME/.config/maza/ || CONFIG=$XDG_CONFIG_HOME/maza/
HOST_FILE=/etc/hosts
COLOR_RED=$(tput setaf 1)
COLOR_GREEN=$(tput setaf 2)
COLOR_RESET=$(tput sgr0)
LIST="list"
LIST_DNSMASQ="dnsmasq.conf"
IGNORE_LIST_DEFAULT="localhost \
localhost.localdomain \
local \
broadcasthost \
ip6-localhost \
ip6-loopback \
ip6-localnet \
ip6-mcastprefix \
ip6-allnodes \
ip6-allrouters \
ip6-allhosts \
0.0.0.0"
IGNORE_LIST_FILE="ignore"
START_TAG="## MAZA - List ad blocking"
PROJECT="### https://github.com/tanrax/maza-ad-blocking"
AUTHOR="### Created by Andros Fenollosa (https://andros.dev/)"
END_TAG="## END MAZA"


# Create sed cross system
custom-sed() {
    if [[ $THIS_OS = *$NAME_OSX* ]]; then
        # Check if OSX and install GSED
        if [ -x "$(command -v gsed)" ]; then
            gsed "$@"
        else
            echo "${COLOR_RED}ERROR. You must install gsed if you are using OSX${COLOR_RESET}"
            exit 1
        fi
    else
        # Linux
        sed "$@"
    fi
}
export -f custom-sed


# FUNCTIONS

## HELP
usage() {
    if [ "$*" != "" ] ; then
        echo "Error: $*"
    fi

    cat << EOF
Usage: $PROGNAME [OPTION]
Simple and efficient local ad blocking throughout the network.

Options:
status       Check if it's active or not
update       Update the list of DNS to be blocked
start        Activate blocking DNS.
stop         Stop blocking DNS.
--help       Display this usage message and exit
EOF

    exit 1
}

status() {
    if grep -qF "$START_TAG" "$HOST_FILE";then
        echo "${COLOR_GREEN}ENABLED${COLOR_RESET}"
    else
        echo "${COLOR_RED}DISABLED${COLOR_RESET}"
    fi
}

update() {
    # Make conf folder
    rm -f "$CONFIG$LIST"
    rm -f "$CONFIG$LIST_DNSMASQ"
    mkdir -p "$CONFIG"
    # Download DNS list
    curl -L -s "$URL_DNS_LIST" -o "$CONFIG$LIST"
    ## Remove comments
    ### Start with #
    custom-sed -i.bak '/^#/ d' "$CONFIG$LIST"
    ### Remove comments in middle of line
    custom-sed -i.bak 's/#.*$//g' "$CONFIG$LIST"
    ### Remove spaces in end of line
    custom-sed -i.bak 's/ *$//g' "$CONFIG$LIST"
    ## Remove "0.0.0.0" or "127.0.0.1"
    custom-sed -i.bak 's/0.0.0.0 //g' "$CONFIG$LIST"
    custom-sed -i.bak 's/127.0.0.1 //g' "$CONFIG$LIST"
    # Make ignore list
    if [ ! -f "$CONFIG$IGNORE_LIST_FILE" ]; then
	echo "$IGNORE_LIST_DEFAULT" | tr " " "\n" > "$CONFIG$IGNORE_LIST_FILE"
    fi
    # Remove ignore list
    while read -r line; do
	custom-sed -i.bak "/$line/d" "$CONFIG$LIST"
    done < "$CONFIG$IGNORE_LIST_FILE"
    ## Remove empty lines
    custom-sed -i.bak '/^$/d' "$CONFIG$LIST"
    # Make dnsmasq format
    cp "$CONFIG$LIST" "$CONFIG$LIST_DNSMASQ"
    ## Remove triple "-". Example: "my---domain.com" to "my-domain.com". Only in dnsmasq.
    custom-sed -i.bak "s/---/-/g" "$CONFIG$LIST_DNSMASQ"
    ## Remove double "-". Example: "my--domain.com" to "my-domain.com". Only in dnsmasq.
    custom-sed -i.bak "s/--/-/g" "$CONFIG$LIST_DNSMASQ"
    ## mydomain.com to address=/mydomain.com/127.0.0.1
    custom-sed -i.bak "s|\(.*\)|address=/\1/127.0.0.1|" "$CONFIG$LIST_DNSMASQ"
    ## Add start tag DNS list in first line
    custom-sed -i.bak "1i\\$AUTHOR" "$CONFIG$LIST"
    custom-sed -i.bak "1i\\$PROJECT" "$CONFIG$LIST"
    custom-sed -i.bak "1i\\$START_TAG" "$CONFIG$LIST"
    ## Add end tag DNS list in first line
    echo "$END_TAG" >> "$CONFIG$LIST"
    ## Add start tag DNS dnsmasq in first line
    custom-sed -i.bak "1i\\$AUTHOR" "$CONFIG$LIST_DNSMASQ"
    custom-sed -i.bak "1i\\$PROJECT" "$CONFIG$LIST_DNSMASQ"
    custom-sed -i.bak "1i\\$START_TAG" "$CONFIG$LIST_DNSMASQ"
    ## Add end tag DNS DNSMASQ in first line
    echo "$END_TAG" >> "$CONFIG$LIST_DNSMASQ"
    # Remove temp file
    rm "$CONFIG$LIST.bak"
    rm "$CONFIG$LIST_DNSMASQ.bak"
    # Notify user
    echo "${COLOR_GREEN}List updated!${COLOR_RESET}"
}

start() {
    update
    # Add List to host file.
    # Transform "mydomain.com" to "127.0.0.1 mydomain.com" except comments
    custom-sed "/^#/!s/^/127.0.0.1 /g" "$CONFIG$LIST" >> "$HOST_FILE"
    # Notify user
    echo "${COLOR_GREEN}ENABLED!${COLOR_RESET}"
}

stop() {
    # Remove list to host file
    custom-sed -i "/$START_TAG/,/$END_TAG/d" "$HOST_FILE"

    # Remove DNSMASQ
    cat /dev/null > "$CONFIG$LIST_DNSMASQ"

    # Notify user
    echo "${COLOR_GREEN}DISABLED!${COLOR_RESET}"
}

# CONTROLE ARGUMENTS
isArg=""

while [ $# -gt 0 ] ; do
    case "$1" in
    --help)
        usage
        ;;
    status)
        isArg="1"
        status
        ;;
    update)
        isArg="1"
        update
        ;;
    start)
        isArg="1"
        start
        ;;
    stop)
        isArg="1"
        stop
        ;;
    *)
    esac
    shift
done

if [ -z $isArg ] ; then
    usage "Not enough arguments"
fi