yt

#!/bin/bash

exe=$(readlink -f "$0")
ui=en

API='https://translate.yandex.net/api/v1.5/tr.json'

say() { echo "$@" >&2; }

error() {
    local -i rc="$1"
    shift
    say "$@"
    exit $rc
}

[ -d ~/.yt/. ] || { mkdir -p ~/.yt; error 1 "No API key."; }
[ -e ~/.yt/key ] || { mkdir -p ~/.yt; error 1 "No API key file."; }

declare -a wants=(
    curl sed jq
    tr cat mktemp rm od
)
for p in "${wants[@]}"; do
    x=$(type -P "$p")
    [ -z "$x" -o ! -x "$x" ] || continue
    error 1 "No '$p' available."
done

temp="$(mktemp -p /tmp)"
[ -f "$temp" ] || error 1 "Cannot write to /tmp/."
trap "rm -f '${temp}'" EXIT

_fetch() { curl -Ssk "$@"; }

fetch() {
    _fetch "$@" > "$temp"
    local code=$(jq .code < "$temp")
    if [ "$code" = 200 ]; then
        : # that's ok
    elif [ "$code" != null ]; then
        local msg=$(jq .message < "$temp")
        local -A rcx=(
            [401]='Bad API key'
            [402]='API key banned'
            [404]='Daily limit exceeded'
            [413]='Text size exceeded'
            [422]='Cannot translate text'
            [501]='Unsupported lang pair'
        )
        [ -n "$msg" ] || msg="= ${rcx[$code]}"
        error 1 "Error #${code}: ${msg}"
    fi
    cat "$temp"
}

api_call() {
    local fn="$1" ; shift
    local tail=$(echo -n "$@" | tr -s '[:space:]' ' ' | sed -e 's/\s\+\(\w\+=\)/\&\1/g')
    local url="${API}/${fn}?key=${APIKEY}${tail:+&}${tail}"
    fetch "${url}"
}

lang_list() {
    api_call getLangs ui=$ui
    # &callback=<имя callback-функции>
    #   {
    #     "dirs": [
    #         "az-ru",
    #         "be-bg",
    #         "be-cs",
    #         "be-de",
    #         ...
    #     ],
    #     "langs": {
    #         "af": "Afrikaans",
    #         "am": "Amharic",
    #         "ar": "Arabic",
    #         "az": "Azerbaijani",
    #         ...
    #     }
    #   }

}

c2x() {
    echo -n "$*" |
    od -vtxC -Anone |           # space prefixed, charwise, 2-hex per char
    tr -d '\n' |                # join lines
    tr '[:lower:]' '[:upper:]'  # uppercase hex
}

urlencode() { c2x "$@" | tr ' ' '%'; }  # 'A' -> '%41' for all, easy way

detect_lang() {
    local hint='en,ru'
    api_call detect "text=$(urlencode "$@")" "hint=${hint}"
    # { "code": 200, "lang": "en" }
}

whereto() {
    local s="$(echo -n "$@" | tr -s '[:space:]' ' ')"
    local l="$(echo -n "$s" | tr -dc '[:alpha:]')"

    # say "#l=${#l} #s=${#s} $(( ${#s} / 2 ))"

    (( ${#l} < ( ${#s} / 2 ) )) && echo 'ru-en' || echo 'ru'
}

translate() {
    local to=ru # where to translate to ('ru') or lang pair (like 'en-ru')
    if [[ "$1" =~ ^[a-z]{2,2}(-[a-z]{2,2})?$ ]]; then
        to="$1"
        shift
    else
        to=$(whereto "$@")
    fi
    local fm=plain # text format ('plain' or 'html')
    api_call translate "text=$(urlencode "$@")" "lang=${to}" "format=${fm}"
    # &options= ?????
    # { "code": 200, "lang": "en-ru", "text": [ "Здравствуй, Мир!" ] }
}

output() { if [ -t 1 ]; then jq ${1:-.}; else cat; fi; }

# see https://translate.yandex.ru/developers/keys
source ~/.yt/key

[ "$1" != -l ] || { lang_list | output; exit; }
[ "$1" != -L ] || { shift; detect_lang "$@" | output; exit; }
[ $# -gt 0 ] && { translate "$@" | output .text[]; } ||
error 1 "Usage: $(basename ${exe}) [-l|-L] [<lang1>[-<lang2>]] text"

# EOF #