#!/bin/sh

# The MIT License (MIT)
#
# Copyright © 2020-2025 pacman64
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the “Software”), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.


# dog [options...] [paths/URIs...]
#
#
# Dog fetches data from the named sources given to it, whether these are
# filenames or URIs. Single dashes stand for standard input, and can't be
# used more than once. When no names are given, stdin is read by default.
#
# A line-mode is available via leading option `-l`, or its aliases `--l`,
# `-lines`, and `--lines`. This mode turns all CRLF byte-pairs into single
# LF bytes, and ensures all non-empty inputs end with a final LF byte,
# which avoids accidentally joining lines across different inputs.
#
# Line-mode also ignores leading UTF-8 BOMs on each input's first line.


# fix_lines ensures CRLF byte-pairs become single LF bytes, and that
# leading UTF-8 BOMs on the first lines of each input are ignored
fix_lines() {
    awk '
        FNR == 1 { gsub(/^\xef\xbb\xbf/, "") }
        { gsub(/\r$/, ""); print; fflush() }
    ' "$@"
}

# fail quits the script right after showing the message given, using
# exit code given as its 2nd arg
fail() {
    printf "\e[31m%s\e[0m\n" "$1" > /dev/stderr
    exit "${2:-1}"
}

# when no args are given, just show the help message and quit
if [ $# -eq 0 ]; then
    fix_lines
    exit $?
fi

# handle leading options
lines=0
case "$1" in
    -h|--h|-help|--help)
        awk '/^# +dog /, /^$/ { gsub(/^# ?/, ""); print }' "$0"
        exit 0
    ;;
    -l|--l|-lines|--lines)
        # enable line-mode
        lines=1
        # don't confuse this option as a named input, later on
        shift
    ;;
esac

# ensure single dashes aren't used multiple times
dashes=0
for a in "$@"; do
    if [ "$a" = "-" ]; then
        if [ "$dashes" -gt 0 ]; then
            fail "can't use stdin (single-dash) more than once" 1
        fi
        dashes=1
    fi
done

# ensure errors propagate correctly, even when in line-mode
# set -o pipefail

for a in "$@"; do
    case "$a" in
        -)
            # handle a dash by reading from stdin
            if [ "$lines" -eq 1 ]; then
                fix_lines || exit $?
            else
                cat || exit $?
            fi
        ;;

        dict://*|file://*|ftp://*|ftps://*|gopher://*|gophers://*|\
        http://*|https://*|rtmp://*|rtsp://*|scp://*|sftp://*|\
        smb://*|smbs://*|telnet://*|tftp://*)
            # handle URIs
            if [ "$lines" -eq 1 ]; then
                { curl -s -L "$a" | fix_lines; } || \
                    fail "failed to fetch URI $a" $?
            else
                curl -s -L "$a" || fail "failed to fetch URI $a" $?
            fi
        ;;

        data:*)
            # handle data-URIs
            if [ "$lines" -eq 1 ]; then
                {
                    printf "%s" "$a" | sed -E 's-^data:.{0,50};base64,--' |
                        base64 -d | fix_lines
                } || fail "failed to decode data-URI $a" $?
            else
                {
                    printf "%s" "$a" | sed -E 's-^data:.{0,50};base64,--' |
                        base64 -d
                } || fail "failed to decode data-URI $a" $?
            fi
        ;;

        *)
            # handle files and bytes-mode data-URIs
            if [ "$lines" -eq 1 ]; then
                fix_lines "$a" || fail "failed to open file $a" $?
            else
                cat "$a" || fail "failed to open file $a" $?
            fi
        ;;
    esac
done