commented sh files

src/sh/api.sh

@@ -1,3 +1,10 @@
+# This file provides the methods for access to several APIs
+#
+# APIs:
+# - MusicBrainz
+# - Discogs
+# - Wikidata
+# - Wikipedia
 if [ ! "${API_LOADED:-}" ]; then
   MB_MAX_RETRIES=10
   MB_BROWSE_STEPS=100
@@ -8,6 +15,16 @@ if [ ! "${API_LOADED:-}" ]; then
   export API_LOADED=1
 fi
 
+# Internal method for MusicBrainz API access
+#
+# @argument $1: entity (see `case` below)
+# @argument $2: MusicBrainz ID
+# @argument $3: offset (optional, but mandatory for browse requests)
+#
+# If the API access fails, then the error message is logged, and at most
+# `MB_MAX_RETRIES` retries are made. If browse requests are made, then at most
+# `MB_BROWSE_STEPS` number of entries are requested per call. The offset in
+# browse request must be specified.
 __api_mb() {
   tmpout=$(mktemp)
   for _ in $(seq "$MB_MAX_RETRIES"); do
@@ -98,35 +115,62 @@ __api_mb() {
   return 1
 }
 
+# The interface to MusicBrainz API.
+
+# Retrieve MusicBrainz artist information
+#
+# @argument $1: MusicBrainz artist ID
 api_mb_artist() {
   __api_mb "artist" "$1"
 }
 
+# Retrieve MusicBrainz release-group information
+#
+# @argument $1: MusicBrainz release-group ID
 api_mb_releasegroup() {
   __api_mb "releasegroup" "$1"
 }
 
+# Retrieve MusicBrainz release information
+#
+# @argument $1: MusicBrainz release ID
 api_mb_release() {
   __api_mb "release" "$1"
 }
 
+# Retrieve MusicBrainz release-groups for given artist
+#
+# @argument $1: MusicBrainz artist ID
+# @argument $2: offset (defaults to 0)
 api_mb_browse_artist_releasegroups() {
   __api_mb "browse-artist-releasegroups" "$1" "${2:-0}"
 }
 
+# Retrieve MusicBrainz releases in given release group
+#
+# @argument $1: MusicBrainz release-group ID
+# @argument $2: offset (defaults to 0)
 api_mb_browse_releasegroup_releases() {
   __api_mb "browse-releasegroup-releases" "$1" "${2:-0}"
 }
 
-# Argument: Search string
+# Search MusicBrainz database for given artist
+#
+# @argument $1: query
 api_mb_search_artist() {
   __api_mb "search-artist" "$1"
 }
 
+# Search MusicBrainz database for given release group
+#
+# @argument $1: query
 api_mb_search_releasegroup() {
   __api_mb "search-releasegroup" "$1"
 }
 
+# Retrieve Discogs artist information
+#
+# @argument $1: Discogs artist ID
 api_discogs_artist() {
   $CURL \
     --get \
@@ -134,6 +178,9 @@ api_discogs_artist() {
     "https://api.discogs.com/artists/$1"
 }
 
+# Retrieve sitelinks from wikidata
+#
+# @argument $1: Wikidata ID
 api_wikidata_sitelinks() {
   $CURL \
     --get \
@@ -141,6 +188,9 @@ api_wikidata_sitelinks() {
     "https://www.wikidata.org/w/rest.php/wikibase/v1/entities/items/$1/sitelinks"
 }
 
+# Retrieve summary from Wikipedia page
+#
+# @argument $1: Wikipedia page name
 api_wikipedia_en_summary() {
   $CURL \
     --get \