Adding support for fish shell (CON-1840)

export.fish

@@ -0,0 +1,76 @@
+# This script should be sourced, not executed.
+
+function realpath_int --description "Simplified realpath helper" --argument-names arg
+    if test -z "$arg"
+        return 1
+    end
+
+    set -l wdir $PWD
+    if test "$PWD" = "/"
+        set wdir ""
+    end
+
+    if string match -rq '^~' -- $arg
+        set arg (string replace -r '^~' $HOME -- $arg)
+    end
+
+    set -l scriptdir ""
+    switch $arg
+        case '/*'
+            set scriptdir $arg
+        case '*'
+            set -l stripped (string replace -r '^\./' '' -- $arg)
+            set scriptdir "$wdir/$stripped"
+    end
+
+    set scriptdir (string replace -r '/[^/]*$' '' -- $scriptdir)
+    if test -z "$scriptdir"
+        set scriptdir "/"
+    end
+    echo $scriptdir
+end
+
+function esp_matter_export_main --description "Initialize ESP Matter environment variables for fish"
+    if not set -q ESP_MATTER_PATH
+        set -l self_path (status --current-filename)
+
+        if test -z "$self_path"
+            echo "Could not detect ESP_MATTER_PATH. Please set it before sourcing this script:" 1>&2
+            echo "  set -gx ESP_MATTER_PATH <add path here>" 1>&2
+            return 1
+        end
+
+        set -l uname_out (uname -s)
+        set -l script_dir ""
+        if string match -q 'Darwin*' -- $uname_out
+            set -l script_dir_guess (realpath_int "$self_path")
+            set script_dir (begin; builtin cd "$script_dir_guess"; pwd; end)
+        else
+            set -l script_name (command readlink -f "$self_path" 2>/dev/null)
+            if test $status -eq 0; and test -n "$script_name"
+                set script_dir (command dirname "$script_name")
+            end
+            if test -z "$script_dir"
+                set script_dir (realpath_int "$self_path")
+                set script_dir (begin; builtin cd "$script_dir"; pwd; end)
+            end
+        end
+
+        set -gx ESP_MATTER_PATH "$script_dir"
+        echo "Setting ESP_MATTER_PATH to '$ESP_MATTER_PATH'"
+    end
+
+    set -l gn_path "$ESP_MATTER_PATH/connectedhomeip/connectedhomeip/.environment/cipd/packages/pigweed/"
+    if not contains -- $gn_path $PATH
+        set -gx PATH $PATH $gn_path
+    end
+
+    set -l host_path "$ESP_MATTER_PATH/connectedhomeip/connectedhomeip/out/host"
+    if not contains -- $host_path $PATH
+        set -gx PATH $PATH $host_path
+    end
+
+    set -gx ZAP_INSTALL_PATH "$ESP_MATTER_PATH/connectedhomeip/connectedhomeip/.environment/cipd/packages/zap"
+end
+
+esp_matter_export_main