1 files changed, 201 insertions, 0 deletions
diff --git a/src/db.sh b/src/db.sh
new file mode 100644
index 0000000..6d733ef
--- /dev/null
+++ b/src/db.sh
@@ -0,0 +1,201 @@
+# Copyright (c) 2016 Egor Tensin <Egor.Tensin@gmail.com>
+# This file is part of the "Configuration file sharing" project.
+# For details, see https://github.com/egor-tensin/config-links.
+# Distributed under the MIT License.
+
+# Shared directory settings
+
+shared_dir="$( pwd )"
+
+update_shared_dir() {
+    if [ "$#" -ne 1 ]; then
+        echo "usage: ${FUNCNAME[0]} DIR" >&2
+        return 1
+    fi
+
+    local new_shared_dir
+    new_shared_dir="$( traverse_path --exist --directory -- "$1" )"
+
+    [ "$db_path" == "$shared_dir/$default_db_name" ] \
+        && db_path="$new_shared_dir/$default_db_name"
+
+    shared_dir="$new_shared_dir"
+}
+
+# Database maintenance
+
+readonly default_db_name='links.bin'
+db_path="$shared_dir/$default_db_name"
+declare -A database
+
+update_database_path() {
+    if [ "$#" -ne 1 ]; then
+        echo "usage: ${FUNCNAME[0]} PATH" >&2
+        return 1
+    fi
+
+    db_path="$( traverse_path --file -- "$1" )"
+
+    local db_dir
+    db_dir="$( dirname -- "$db_path" )"
+    mkdir -p -- "$db_dir"
+}
+
+ensure_database_exists() {
+    [ -f "$db_path" ] || is_dry_run || > "$db_path"
+}
+
+read_database() {
+    [ ! -f "$db_path" ] && is_dry_run && return 0
+
+    local entry
+    while IFS= read -d '' -r entry; do
+        database[$entry]=1
+    done < "$db_path"
+}
+
+write_database() {
+    is_dry_run && return 0
+
+    > "$db_path"
+
+    local entry
+    for entry in "${!database[@]}"; do
+        printf -- '%s\0' "$entry" >> "$db_path"
+    done
+}
+
+delete_obsolete_dirs() {
+    if [ "$#" -ne 2 ]; then
+        echo "usage: ${FUNCNAME[0]} BASE_DIR DIR" >&2
+        return 1
+    fi
+
+    is_dry_run && return 0
+
+    local base_dir="$1"
+    local dir="$2"
+
+    base_dir="$( traverse_path --exist --directory -- "$base_dir" )"
+    dir="$( traverse_path --exist --directory -- "$dir" )"
+
+    [ "$base_dir" == "$dir" ] && return 0
+
+    local subpath="${dir##$base_dir/}"
+
+    if [ "$subpath" == "$dir" ]; then
+        dump "base directory: $base_dir"    >&2
+        dump "... is not a parent of: $dir" >&2
+        return 1
+    fi
+
+    ( cd -- "$base_dir/" && rmdir -p --ignore-fail-on-non-empty -- "$subpath" )
+}
+
+delete_obsolete_entries() {
+    local entry
+    for entry in "${!database[@]}"; do
+        dump "entry: $entry"
+        unset -v 'database[$entry]'
+
+        local var_name
+        var_name="$( extract_variable_name "$entry" )" || continue
+        cache_variable "$var_name"
+
+        local symlink_var_dir
+        symlink_var_dir="$( resolve_variable "$var_name" )" || continue
+        local shared_var_dir="$shared_dir/%$var_name%"
+        local subpath="${entry#%$var_name%/}"
+        local symlink_path="$symlink_var_dir/$subpath"
+        local shared_path="$shared_var_dir/$subpath"
+
+        dump "    shared file path: $shared_path"
+        dump "    symlink path: $symlink_path"
+
+        if [ ! -L "$shared_path" ] && [ ! -e "$shared_path" ]; then
+            dump '    the shared file is missing, so going to delete the symlink'
+            is_dry_run && continue
+
+            if [ ! -L "$symlink_path" ]; then
+                dump "    not a symlink or doesn't exist, so won't delete"
+                continue
+            fi
+
+            local target_path
+            target_path="$( traverse_path -- "$symlink_path" )"
+
+            if [ "$shared_path" != "$target_path" ]; then
+                dump "    doesn't point to the shared file, so won't delete"
+                continue
+            fi
+
+            rm -f -- "$symlink_path"
+
+            local symlink_dir
+            symlink_dir="$( dirname -- "$symlink_path" )"
+            delete_obsolete_dirs "$symlink_var_dir" "$symlink_dir" || true
+
+            continue
+        fi
+
+        if [ ! -L "$symlink_path" ]; then
+            dump "    not a symlink or doesn't exist"
+            continue
+        fi
+
+        local target_path
+        target_path="$( traverse_path -- "$symlink_path" )"
+
+        if [ "$target_path" != "$shared_path" ]; then
+            dump "    doesn't point to the shared file"
+            continue
+        fi
+
+        dump '    ... points to the shared file'
+        database[$entry]=1
+    done
+}
+
+discover_new_entries() {
+    local shared_var_dir
+    while IFS= read -d '' -r shared_var_dir; do
+        dump "shared directory: $shared_dir/$shared_var_dir"
+
+        local var_name
+        var_name="$( extract_variable_name "$shared_var_dir" )"
+        cache_variable "$var_name"
+
+        shared_var_dir="$shared_dir/$shared_var_dir"
+
+        local symlink_var_dir
+        symlink_var_dir="$( resolve_variable "$var_name" )" || continue
+        dump "    symlinks directory: $symlink_var_dir"
+
+        local shared_path
+        while IFS= read -d '' -r shared_path; do
+            dump "        shared file path: $shared_path"
+
+            local entry="%$var_name%/${shared_path:${#shared_var_dir}}"
+
+            if [ -n "${database[$entry]+x}" ]; then
+                dump '        ... already has a symlink'
+                continue
+            fi
+
+            local subpath="${shared_path:${#shared_var_dir}}"
+            local symlink_path="$symlink_var_dir/$subpath"
+
+            dump "        symlink path: $symlink_path"
+
+            is_dry_run && continue
+
+            local symlink_dir
+            symlink_dir="$( dirname -- "$symlink_path" )"
+            mkdir -p -- "$symlink_dir"
+            ln -f -s --no-target-directory -- "$shared_path" "$symlink_path"
+
+            database[$entry]=1
+        done < <( find "$shared_var_dir" -type f -print0 )
+
+    done < <( find "$shared_dir" -regextype posix-basic -mindepth 1 -maxdepth 1 -type d -regex ".*/$var_name_regex\$" -printf '%P/\0' )
+}