#compdef beet

# zsh completion for beets music library manager and MusicBrainz tagger: https://beets.io/

# Default values for BEETS_LIBRARY & BEETS_CONFIG needed for the cache checking function.
# They will be updated under the assumption that the config file is in the same directory as the library.
local BEETS_LIBRARY=~/.config/beets/library.db
local BEETS_CONFIG=~/.config/beets/config.yaml
# Use separate caches for file locations, command completions, and query completions.
# This allows the use of different rules for when to update each one.
zstyle ":completion:${curcontext%:*}:*" cache-policy _beet_check_cache
zstyle ":completion:${curcontext%:*}:*" use-cache true
_beet_check_cache () {
    local cachefile="$(basename ${1})"
    if [[ ! -a "${1}" ]] || [[ "${1}" -ot =beet ]]; then
	# always update the cache if it doesn't exist, or if the beet executable changes
	return 0
    fi
    case cachefile; in
	(beetslibrary)
	    if [[ ! -a "${~BEETS_LIBRARY}" ]] || [[ "${1}" -ot "${~BEETS_CONFIG}" ]]; then
		return 0
	    fi
	    ;;
	(beetscmds)
	    _retrieve_cache beetslibrary
	    if [[ "${1}" -ot "${~BEETS_CONFIG}" ]]; then
		return 0
	    fi
	    ;;
    esac
    return 1
}

# useful: argument to _regex_arguments for matching any word
local matchany=/$'[^\0]##\0'/
# arguments to _regex_arguments for completing files and directories
local -a files dirs
files=("$matchany" ':file:file:_files')
dirs=("$matchany" ':dir:directory:_dirs')

# Retrieve or update caches
if ! _retrieve_cache beetslibrary || _cache_invalid beetslibrary; then
    local BEETS_LIBRARY="${$(beet config|grep library|cut -f 2 -d ' '):-${BEETS_LIBRARY}}"
    local BEETS_CONFIG="${$(beet config -p):-${BEETS_CONFIG}}"
    _store_cache beetslibrary BEETS_LIBRARY BEETS_CONFIG
fi

if ! _retrieve_cache beetscmds || _cache_invalid beetscmds; then
    local -a subcommands fields beets_regex_words_subcmds beets_regex_words_help query modify
    local subcmd cmddesc matchquery matchmodify field fieldargs queryelem modifyelem
    # Useful function for joining grouped lines of output into single lines (taken from _completion_helpers)
    _join_lines() {
	awk -v SEP="$1" -v ARG2="$2" -v START="$3" -v END2="$4" 'BEGIN {if(START==""){f=1}{f=0};
         if(ARG2 ~ "^[0-9]+"){LINE1 = "^[[:space:]]{0,"ARG2"}[^[:space:]]"}else{LINE1 = ARG2}}
         ($0 ~ END2 && f>0 && END2!="") {exit}
         ($0 ~ START && f<1) {f=1; if(length(START)!=0){next}}
         ($0 ~ LINE1 && f>0) {if(f<2){f=2; printf("%s",$0)}else{printf("\n%s",$0)}; next}
         (f>1) {gsub(/^[[:space:]]+|[[:space:]]+$/,"",$0); printf("%s%s",SEP, $0); next}
         END {print ""}'
    }
    # Variables used for completing subcommands and queries
    subcommands=(${${(f)"$(beet help | _join_lines ' ' 3 'Commands:')"}[@]})
    fields=($(beet fields | grep -G '^  ' | sort -u | colrm 1 2))
    for field in "${fields[@]}"
    do
	fieldargs="$fieldargs '$field:::{_beet_field_values $field}'"
    done
    queryelem="_values -S : 'query field (add an extra : to match by regexp)' '::' $fieldargs"
    modifyelem="_values -S = 'modify field (replace = with ! to remove field)' $(echo "'${^fields[@]}:: '")"
    # regexps for matching query and modify terms on the command line
    matchquery=/"(${(j/|/)fields[@]})"$':[^\0]##\0'/
    matchmodify=/"(${(j/|/)fields[@]})"$'(=[^\0]##|!)\0'/
    # create completion function for queries
    _regex_arguments _beet_query "$matchany" \# \( "$matchquery" ":query:query string:$queryelem" \) \#
    local "beets_query"="$(which _beet_query)"
    # arguments for _regex_arguments for completing lists of queries and modifications
    beets_query_args=( \( "$matchquery" ":query:query string:{_beet_query}" \) \# )
    beets_modify_args=( \( "$matchmodify" ":modify:modify string:$modifyelem" \) \# )
    # now build arguments for _beet and _beet_help completion functions
    beets_regex_words_subcmds=('(')
    for i in ${subcommands[@]}; do
	subcmd="${i[(w)1]}"
	# remove first word and parenthesised alias, replace : with -, [ with (, ] with ), and remove single quotes
	cmddesc="${${${${${i[(w)2,-1]##\(*\) #}//:/-}//\[/(}//\]/)}//\'/}"
	# update arguments needed for creating _beet
	beets_regex_words_subcmds+=(/"${subcmd}"$'\0'/ ":subcmds:subcommands:((${subcmd}:${cmddesc// /\ }))")
	beets_regex_words_subcmds+=(\( "${matchany}" ":option:option:{_beet_subcmd ${subcmd}}" \) \# \|)
	# update arguments needed for creating _beet_help
	beets_regex_words_help+=("${subcmd}:${cmddesc}")
    done
    beets_regex_words_subcmds[-1]=')'
    _store_cache beetscmds beets_regex_words_subcmds beets_regex_words_help beets_query_args beets_modify_args beets_query
else
    # Evaluate the variable containing the query completer function
    eval "${beets_query}"
fi

# Function for getting unique values for field from database (you may need to change the path to the database).
_beet_field_values() {
    local -a output fieldvals
    local sqlcmd="select distinct $1 from items;"
    _retrieve_cache beetslibrary
    case ${1}
    in
        lyrics)
            fieldvals=
            ;;
        *)
	    if [[ "$(sqlite3 ${~BEETS_LIBRARY} ${sqlcmd} 2>&1)" =~ "no such column" ]]; then
		sqlcmd="select distinct value from item_attributes where key=='$1' and value!='';"
	    fi
	    output="$(sqlite3 -list -noheader ${~BEETS_LIBRARY} ${sqlcmd} 2>/dev/null)"
            fieldvals=("${(f)output[@]}")
            ;;
    esac
    compadd -P \" -S \" -M 'm:{[:lower:][:upper:]}={[:upper:][:lower:]}' -Q -a fieldvals
}

# This function takes a beet subcommand as its first argument, and then uses _regex_words to set ${reply[@]}
# to an array containing arguments for the _regex_arguments function.
_beet_subcmd_options() {
    local shortopt optarg optdesc
    local matchany=/$'[^\0]##\0'/
    local -a regex_words
    regex_words=()
    for i in ${${(f)"$(beet help $1 | awk '/^ +-/{if(x)print x;x=$0;next}/^ *$/{if(x) exit}{if(x) x=x$0}END{print x}')"}[@]}
    do
        opt="${i[(w)1]/,/}"
        optarg="${${${i## #[-a-zA-Z]# }##[- ]##*}%%[, ]*}"
        optdesc="${${${${${i[(w)2,-1]/[A-Z, ]#--[-a-z]##[=A-Z]# #/}//:/-}//\[/(}//\]/)}//\'/}"
        case $optarg; in
            ("")
                if [[ "$1" == "import" && "$opt" == "-L" ]]; then
                    regex_words+=("$opt:$optdesc:\${beets_query_args[@]}")
                else
                    regex_words+=("$opt:$optdesc")
                fi
                ;;
            (LOG)
		local -a files
		files=("$matchany" ':file:file:_files')
		regex_words+=("$opt:$optdesc:\$files")
                ;;
            (CONFIG)
                local -a configfile
                configfile=("$matchany" ':file:config file:{_files -g *.yaml}')
                regex_words+=("$opt:$optdesc:\$configfile")
                ;;
            (LIB|LIBRARY)
                local -a libfile
                libfile=("$matchany" ':file:database file:{_files -g *.db}')
                regex_words+=("$opt:$optdesc:\$libfile")
                ;;
            (DIR|DIRECTORY|DEST)
		local -a dirs
		dirs=("$matchany" ':dir:directory:_dirs')
                regex_words+=("$opt:$optdesc:\$dirs")
                ;;
            (SOURCE)
                if [[ "${1}" -eq lastgenre ]]; then
                    local -a lastgenresource
                    lastgenresource=(/$'(artist|album|track)\0'/ ':source:genre source:(artist album track)')
                    regex_words+=("$opt:$optdesc:\$lastgenresource")
                else
                    regex_words+=("$opt:$optdesc:\$matchany")
                fi
                ;;
            (*)
                regex_words+=("$opt:$optdesc:\$matchany")
                ;;
        esac
    done
    _regex_words options "$1 options" "${regex_words[@]}"
}

## Function for completing subcommands. It calls another completion function which is first created if it doesn't already exist.
_beet_subcmd() {
    local -a options
    local subcmd="${1}"
    if [[ ! $(type _beet_${subcmd} | grep function) =~ function ]]; then
	if ! _retrieve_cache "beets${subcmd}" || _cache_invalid "beets${subcmd}"; then
	    local matchany=/$'[^\0]##\0'/
	    local -a files
	    files=("$matchany" ':file:file:_files')
	    # get arguments for completing subcommand options
	    _beet_subcmd_options "$subcmd"
	    options=("${reply[@]}" \#)
	    _retrieve_cache beetscmds
	    case ${subcmd}; in
		(import)
		    _regex_arguments _beet_import "${matchany}" /"${subcmd}"$'\0'/ "${options[@]}" "${files[@]}" \#
		    ;;
		(modify)
		    _regex_arguments _beet_modify "${matchany}" /"${subcmd}"$'\0'/ "${options[@]}" \
				     "${beets_query_args[@]}" "${beets_modify_args[@]}"
		    ;;
		(fields|migrate|version|config)
		    _regex_arguments _beet_${subcmd} "${matchany}" /"${subcmd}"$'\0'/ "${options[@]}"
		    ;;
		(help)
		    _regex_words subcmds "subcommands" "${beets_regex_words_help[@]}"
		    _regex_arguments _beet_help "${matchany}" /$'help\0'/ "${options[@]}" "${reply[@]}"
		    ;;
		(*) # Other commands have options followed by a query
		    _regex_arguments _beet_${subcmd} "${matchany}" /"${subcmd}"$'\0'/ "${options[@]}" "${beets_query_args[@]}"
		    ;;
	    esac
	    # Store completion function in a cache file
	    local "beets_${subcmd}"="$(which _beet_${subcmd})"
	    _store_cache "beets${subcmd}" "beets_${subcmd}"
	else
	    # Evaluate the function which is stored in $beets_${subcmd}
	    local var="beets_${subcmd}"
	    eval "${(P)var}"
	fi
    fi
    _beet_${subcmd}
}

# Global options
local -a globalopts
_regex_words options "global options" '-c:path to configuration file:$files' '-v:print debugging information' \
	     '-l:library database file to use:$files' '-h:show this help message and exit' '-d:destination music directory:$dirs'
globalopts=("${reply[@]}")

# Create main completion function
_regex_arguments _beet "$matchany" \( "${globalopts[@]}" \# \) "${beets_regex_words_subcmds[@]}"

# Set tag-order so that options are completed separately from arguments
zstyle ":completion:${curcontext}:" tag-order '! options'

# Execute the completion function
_beet "$@"

# Local Variables:
# mode:shell-script
# End:
