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Linux/Development/generate-config.sh

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+#!/bin/bash
+
+# Enable strict error handling
+set -e
+
+# Function to show usage instructions
+show_usage() {
+  echo "Usage: $0 [file extensions] [environment] [--dry-run]"
+  echo "  file extensions: A space-separated list of file extensions (e.g. .yml .json .conf)."
+  echo "  environment: The target environment (e.g., development or production)."
+  echo "  --dry-run  : Simulate changes without modifying files."
+}
+
+# Parse command-line arguments
+DRY_RUN=false
+ENV=$1
+if [[ -z "$ENV" ]]; then
+  show_usage
+  exit 1
+fi
+
+if [[ "$2" == "--dry-run" ]]; then
+  DRY_RUN=true
+fi
+
+shift  # Shift arguments so we can get the file extensions after the environment
+
+EXTENSIONS=("$@")
+if [[ ${#EXTENSIONS[@]} -eq 0 ]]; then
+  echo "Error: You must specify at least one file extension."
+  show_usage
+  exit 1
+fi
+
+echo "Arguments passed correctly!"
+
+# Load the appropriate .env file
+if [ -f ".env.$ENV" ]; then
+  set -a
+  source ".env.$ENV"
+  set +a
+else
+  echo "Environment file .env.$ENV not found!"
+  exit 1
+fi
+
+# Function to escape all special characters that might affect sed
+escape_sed_special_chars() {
+  printf '%s' "$1" | sed 's|[&/\$]|\&|g; s|[[:space:]]|\\ |g; s|\\|\\\\|g'
+}
+
+# Process files for each extension
+for EXT in "${EXTENSIONS[@]}"; do
+  # Find and process all *.template files with the current extension, including subdirectories
+  find . -name "*.template$EXT" | while read -r TEMPLATE_FILE; do
+    # Derive output file name by removing ".template"
+    OUTPUT_FILE="${TEMPLATE_FILE%.template$EXT}$EXT"
+
+    # Dry-run reporting or actual processing
+    if $DRY_RUN; then
+      echo "Dry run: would generate $OUTPUT_FILE from $TEMPLATE_FILE"
+
+      LINE_NUMBER=0
+      while IFS= read -r line || [[ -n "$line" ]]; do
+        LINE_NUMBER=$((LINE_NUMBER + 1))
+        while [[ "$line" =~ (\$\{([A-Za-z_][A-Za-z0-9_]*)\}) ]]; do
+          PLACEHOLDER="${BASH_REMATCH[1]}"
+          VAR_NAME="${BASH_REMATCH[2]}"
+          VAR_VALUE="${!VAR_NAME:-<UNDEFINED>}"
+
+          echo "  Would have inputted '$VAR_VALUE' in place of '$VAR_NAME' in $OUTPUT_FILE at line $LINE_NUMBER"
+
+          if [[ "$VAR_VALUE" == "<UNDEFINED>" ]]; then
+            echo "  Warning: Variable '$VAR_NAME' is undefined and will cause an error in actual mode."
+          fi
+
+          line="${line/$PLACEHOLDER/}"
+        done
+      done < "$TEMPLATE_FILE"
+
+    else
+      # Validate unresolved placeholders
+      UNRESOLVED=$(grep -oP '\${\K[A-Za-z_][A-Za-z0-9_]*(?=})' "$TEMPLATE_FILE" | while read -r var; do
+        if [ -z "${!var}" ]; then
+          echo "$var"
+        fi
+      done)
+
+      if [ -n "$UNRESOLVED" ]; then
+        echo "Error: Unresolved variable placeholders detected in $TEMPLATE_FILE!"
+        echo "Ensure all variables are defined in .env.$ENV. Missing: $UNRESOLVED"
+        exit 1
+      fi
+
+      # Backup existing output file if it exists
+      if [ -f "$OUTPUT_FILE" ]; then
+        mv "$OUTPUT_FILE" "${OUTPUT_FILE}.bak"
+        echo "Backup created for $OUTPUT_FILE as ${OUTPUT_FILE}.bak"
+      fi
+
+      # Replace placeholders with environment variables
+      sed_script=""
+      while IFS='=' read -r key value; do
+        # Skip invalid variable names
+        if [[ "$key" =~ ^[A-Za-z_][A-Za-z0-9_]*$ ]]; then
+          # Escape special characters in the key and value for sed
+          escaped_key=$(escape_sed_special_chars "${key}")
+          escaped_value=$(escape_sed_special_chars "${!key}")
+          sed_script+="s|\${${escaped_key}}|${escaped_value}|g;"
+        fi
+      done < <(env)
+
+      # Generate the output file
+      sed -e "$sed_script" "$TEMPLATE_FILE" > "$OUTPUT_FILE"
+      echo "Generated $OUTPUT_FILE from $TEMPLATE_FILE"
+    fi
+  done
+done
+
+# Keep the terminal open at the end
+echo "Script completed. Press any key to exit..."
+read -n 1 -s