Initial commit

skills/get-git-diff/scripts/validate.sh

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+#!/usr/bin/env bash
+#
+# Git Validation Functions
+#
+# Functions for validating git repositories and commit references.
+#
+# Author: Claude Code get-git-diff skill
+# Version: 1.0.0
+
+set -euo pipefail
+
+#######################################
+# Check if in a git repository
+# Returns:
+#   0 if in git repo, 1 if not
+#######################################
+is_git_repo() {
+    git rev-parse --is-inside-work-tree >/dev/null 2>&1
+}
+
+#######################################
+# Validate that a commit reference exists
+# Arguments:
+#   $1 - commit reference (hash, branch, tag)
+# Returns:
+#   0 if valid, 1 if invalid
+# Outputs:
+#   Full commit hash if valid, error message to stderr if invalid
+#######################################
+validate_commit() {
+    local commit_ref="$1"
+    local full_hash
+
+    if full_hash=$(git rev-parse --verify "${commit_ref}" 2>/dev/null); then
+        echo "${full_hash}"
+        return 0
+    else
+        echo "Error: Invalid commit reference: ${commit_ref}" >&2
+        return 1
+    fi
+}
+
+#######################################
+# Validate two commit references
+# Arguments:
+#   $1 - first commit reference
+#   $2 - second commit reference
+# Returns:
+#   0 if both valid, 1 if either invalid
+# Outputs:
+#   Tab-separated full hashes if valid
+#######################################
+validate_commit_pair() {
+    local commit1="$1"
+    local commit2="$2"
+    local hash1 hash2
+
+    if hash1=$(validate_commit "${commit1}") && hash2=$(validate_commit "${commit2}"); then
+        echo "${hash1}	${hash2}"
+        return 0
+    else
+        return 1
+    fi
+}
+
+# Allow script to be sourced or run directly
+if [[ "${BASH_SOURCE[0]}" == "${0}" ]]; then
+    # Example usage
+    if [[ $# -eq 0 ]]; then
+        echo "Usage: $0 <commit-ref> [<commit-ref2>]"
+        echo ""
+        echo "Examples:"
+        echo "  $0 HEAD"
+        echo "  $0 abc123 def456"
+        exit 1
+    fi
+
+    if is_git_repo; then
+        if [[ $# -eq 1 ]]; then
+            validate_commit "$1"
+        else
+            validate_commit_pair "$1" "$2"
+        fi
+    else
+        echo "Error: Not in a git repository" >&2
+        exit 1
+    fi
+fi