e3.run

#!/usr/bin/env bash
PATH=.

usage() {
	echo "Usage: $0 [--keys | --data | KEY] <json_file>"
    echo "  Only one of the following will be printed:"
	echo "  --keys          Print all keys from the JSON file"
    echo "  --data          Print all data from the JSON file"
    echo "  KEY             A hierarchical key (dot separated) to extract its value"
    echo "  <json_file>       The JSON file to process"
    exit 1
}

if [ "$#" -lt 1 ]; then
    usage
fi

keys_flag=0
data_flag=0
specific_key=""
json_file=""

while [ "$#" -gt 0 ]; do
    case "$1" in
        --keys)
            keys_flag=1 ;;
        --data)
            data_flag=1 ;;
        *)
            if [ "$#" -eq 1 ]; then
                json_file="$1"
            else
                specific_key="$1"
            fi
            ;;
    esac
    shift
done

if [ -z "$json_file" ]; then
    echo "Error: JSON file not specified"
    usage
fi

if [ ! -r "$json_file" ]; then
    echo "Error: File '$json_file' does not exist or is not readable"
    usage
fi

json=$(<"$json_file")

print_all_keys() {
    local pos=0
    local len=${#json}

    while [ $pos -lt $len ]; do
        if [ "${json:$pos:1}" = "\"" ]; then
            pos=$((pos+1))
            local start=$pos

            while [ $pos -lt $len ] && [ "${json:$pos:1}" != "\"" ]; do
                pos=$((pos+1))
            done

            local candidate="${json:$start:$((pos-start))}"
            local rest="${json:$((pos+1))}"

            while [ -n "$rest" ] && [[ "${rest:0:1}" =~ [[:space:]] ]]; do
                rest="${rest:1}"
            done

            if [ "${rest:0:1}" = ":" ]; then
                echo "$candidate"
            fi
        else
            pos=$((pos+1))
        fi
    done
}

print_all_data() {
    local pos=0
    local len=${#json}

    while [ $pos -lt $len ]; do
        if [ "${json:$pos:1}" = ":" ]; then
            pos=$((pos+1))

            while [ $pos -lt $len ] && [[ "${json:$pos:1}" =~ [[:space:]] ]]; do
                pos=$((pos+1))
            done
            local first_char="${json:$pos:1}"

            if [ "$first_char" = "\"" ]; then
                pos=$((pos+1))
                local start=$pos

                while [ $pos -lt $len ] && [ "${json:$pos:1}" != "\"" ]; do
                    pos=$((pos+1))
                done
                echo "${json:$start:$((pos-start))}"

            elif [ "$first_char" = "{" ] || [ "$first_char" = "[" ]; then
                local start_char="$first_char"
                local end_char

                if [ "$start_char" = "{" ]; then
                    end_char="}"
                else
                    end_char="]"
                fi

                local count=0
                local start=$pos
                while [ $pos -lt $len ]; do
                    local ch="${json:$pos:1}"

                    if [ "$ch" = "$start_char" ]; then
                        count=$((count+1))
                    elif [ "$ch" = "$end_char" ]; then
                        count=$((count-1))

                        if [ $count -eq 0 ]; then
                            pos=$((pos+1))
                            break
                        fi
                    fi
                    pos=$((pos+1))
                done
                echo "${json:$start:$((pos-start))}"
            else
                local start=$pos
                while [ $pos -lt $len ]; do
                    local ch="${json:$pos:1}"

                    if [ "$ch" = "," ] || [ "$ch" = "}" ] || [ "$ch" = "]" ] || [[ "$ch" =~ [[:space:]] ]]; then
                        break
                    fi
                    pos=$((pos+1))
                done

                local result="${json:$start:$((pos-start))}"
                shopt -s extglob
                result="${result%%+([[:space:]])}"
                echo "$result"
            fi
        else
            pos=$((pos+1))
        fi
    done
}

extract_value() {
    local json_input="$1"
    local key="$2"
    local search="\"$key\""
    local temp="${json_input#*$search}"

    if [ "$temp" = "$json_input" ]; then
         echo "KEY_NOT_FOUND"
         return 1
    fi

    temp="${temp#*:}"
    temp="${temp#"${temp%%[![:space:]]*}"}"
    local first_char="${temp:0:1}"

    if [ "$first_char" = "\"" ]; then
         temp="${temp:1}"
         local value="${temp%%\"*}"
         echo "$value"
         return 0

    elif [ "$first_char" = "{" ] || [ "$first_char" = "[" ]; then
         local start_char="$first_char"
         local end_char

         if [ "$start_char" = "{" ]; then
             end_char="}"
         else
             end_char="]"
         fi

         local count=0
         local pos=0
         local len=${#temp}
         local extracted=""

         while [ $pos -lt $len ]; do
              local ch="${temp:$pos:1}"
              extracted="${extracted}${ch}"

              if [ "$ch" = "$start_char" ]; then
                  count=$((count+1))
              elif [ "$ch" = "$end_char" ]; then
                  count=$((count-1))

                  if [ $count -eq 0 ]; then
                      pos=$((pos+1))
                      break
                  fi
              fi
              pos=$((pos+1))
         done
         echo "$extracted"
         return 0
    else
         local value=""
         local pos=0
         local len=${#temp}

         while [ $pos -lt $len ]; do
             local ch="${temp:$pos:1}"
             if [ "$ch" = "," ] || [ "$ch" = "}" ] || [ "$ch" = "]" ] || [[ "$ch" =~ [[:space:]] ]]; then
                  break
             fi
             value="${value}${ch}"
             pos=$((pos+1))
         done
         echo "$value"
         return 0
    fi
}

extract_hierarchical_value() {
    local current_json="$1"
    local key_path="$2"
    local key="${key_path%%.*}"
    local rest=""

    if [ "$key_path" != "$key" ]; then
         rest="${key_path#*.}"
    fi
    local value
    value=$(extract_value "$current_json" "$key")

    if [ "$value" = "KEY_NOT_FOUND" ]; then
         echo "Key not found: $key_path"
         return 1
    fi

    if [ -n "$rest" ]; then
         echo "$(extract_hierarchical_value "$value" "$rest")"
    else
         echo "$value"
    fi
}

if [ $keys_flag -eq 1 ]; then
    print_all_keys
elif [ $data_flag -eq 1 ]; then
    print_all_data
elif [ -n "$specific_key" ]; then
    extract_hierarchical_value "$json" "$specific_key"
else
    echo "No valid operation specified."
    usage
fi