If a caveman had to make curl, or wget

caveget

#!/usr/bin/env bash

function cavemanget() {
    local URL=$1

    if [ "$URL" = "" ]; then
        echo "A caveman version of wget"
        echo "Usage: $0 \"URL\""
        return 1
    fi

    local PROTO="$(echo "$URL" | grep :// | sed -e's,^\(.*://\).*,\1,g')"
    local URL_NO_PROTO="$(echo "${URL/$PROTO/}")"
    local HOST="$(echo "$URL_NO_PROTO" | cut -d/ -f1)"
    local URL_PATH="$(echo "$URL_NO_PROTO" | grep / | cut -d/ -f2-)"

    if [[ ! $URL =~ "://" ]]; then
        PROTO="http://"
    fi

    local PORT=80
    local OPENSSL=""
    if [ "$PROTO" == "https://" ]; then
        PORT=443
        OPENSSL="1"
    fi

    if [ "$OPENSSL" = "" ]; then
        exec 3<>/dev/tcp/"$HOST/$PORT"
        echo -e "GET /${URL_PATH} HTTP/1.1\r\nHost: ${HOST}\r\nConnection: close\r\n\r\n" >&3
    else
        exec 3< <(echo -e "GET /${URL_PATH} HTTP/1.1\r\nHost: ${HOST}\r\nConnection: close\r\n\r\n" | openssl s_client -quiet -ignore_unexpected_eof -connect "$HOST:$PORT" 2>/dev/null)
    fi

    local CONTENT_TYPE=""
    local FILENAME=""
    local DISPOSITION=""
    local IS_TEXT=0
    local IS_JSON=0
    local HTTP_START=0

    while read -r line; do
        local line_lower=$(echo "$line" | tr '[:upper:]' '[:lower:]')

        if [[ $HTTP_START -eq 0 && "$line" =~ ^HTTP/ ]]; then
            HTTP_START=1
            continue
        fi

        if [[ $HTTP_START -eq 1 ]]; then

            if [[ "$line_lower" =~ ^content-type: ]]; then
                CONTENT_TYPE="${line_lower#*: }"
                if [[ "$CONTENT_TYPE" =~ text/ ]]; then
                    IS_TEXT=1
                fi
                if [[ "$CONTENT_TYPE" =~ application/json ]]; then
                    IS_TEXT=1
                    IS_JSON=1
                fi
            fi

            if [[ "$line_lower" =~ ^content-disposition: ]]; then
                DISPOSITION="${line#*: }"
                if [[ "$DISPOSITION" =~ filename=([^;]+) ]]; then
                    FILENAME="${BASH_REMATCH[1]}"
                fi
            fi

            if [[ "$line" == $'\r' ]]; then
                break
            fi
        fi
    done <&3

    if [ "$IS_TEXT" -eq 1 ]; then
        if command -v jq >/dev/null && [ "$IS_JSON" -eq 1 ]; then
            cat <&3 | jq .
        else
            cat <&3
        fi
    else
        if [ "$FILENAME" = "" ]; then
            FILENAME=$(basename "$URL")
        fi

        echo "Enter the directory to save the file (or press Enter to use the current directory):"
        read -r SAVE_DIR
        if [ "$SAVE_DIR" = "" ]; then
            SAVE_DIR="."
        fi
        echo "Enter a filename (or press Enter to use '$FILENAME'):"
        read -r USER_FILENAME
        if [ "$USER_FILENAME" != "" ]; then
            FILENAME="$USER_FILENAME"
        fi
        local SAVE_PATH="${SAVE_DIR%/}/$FILENAME"
        cat <&3 > "$SAVE_PATH"
        echo "Saved to $SAVE_PATH"
    fi

    exec 3>&-
}

cavemanget "$1"