feat: enhance function default parameter support and fix parsing bugs

ir/inspector.go

@@ -1169,6 +1169,73 @@ func (i *Inspector) buildFunctions(ctx context.Context, schema *IR, targetSchema
 	return nil
 }
 
+// splitParameterString splits a parameter string by commas, but respects quotes,
+// parentheses, and brackets. This handles complex defaults like '{1,2,3}' or '{"key": "value"}'
+func splitParameterString(signature string) []string {
+	var params []string
+	var current strings.Builder
+	depth := 0        // Track nesting depth of (), [], {}
+	inQuote := false  // Track if we're inside a string literal
+
+	i := 0
+	for i < len(signature) {
+		ch := rune(signature[i])
+
+		switch ch {
+		case '\'':
+			// Toggle quote state, but handle escaped quotes
+			if !inQuote {
+				inQuote = true
+				current.WriteRune(ch)
+				i++
+			} else {
+				// Check if this is an escaped quote (two single quotes)
+				if i+1 < len(signature) && signature[i+1] == '\'' {
+					current.WriteRune(ch)
+					current.WriteRune('\'')
+					i += 2 // Skip both quotes
+				} else {
+					inQuote = false
+					current.WriteRune(ch)
+					i++
+				}
+			}
+		case '(', '[', '{':
+			if !inQuote {
+				depth++
+			}
+			current.WriteRune(ch)
+			i++
+		case ')', ']', '}':
+			if !inQuote {
+				depth--
+			}
+			current.WriteRune(ch)
+			i++
+		case ',':
+			if !inQuote && depth == 0 {
+				// This comma is a parameter separator
+				params = append(params, strings.TrimSpace(current.String()))
+				current.Reset()
+			} else {
+				// This comma is inside quotes or nested structure
+				current.WriteRune(ch)
+			}
+			i++
+		default:
+			current.WriteRune(ch)
+			i++
+		}
+	}
+
+	// Add the last parameter
+	if current.Len() > 0 {
+		params = append(params, strings.TrimSpace(current.String()))
+	}
+
+	return params
+}
+
 // parseParametersFromSignature parses function signature string into Parameter structs
 // Example signature: "order_id integer, discount_percent numeric DEFAULT 0"
 // Or with modes: "IN order_id integer, OUT result integer"
@@ -1180,8 +1247,8 @@ func (i *Inspector) parseParametersFromSignature(signature string) []*Parameter
 	var parameters []*Parameter
 	position := 1
 
-	// Split by comma to get individual parameters
-	paramStrings := strings.Split(signature, ",")
+	// Split by comma to get individual parameters (smart split that respects quotes/brackets)
+	paramStrings := splitParameterString(signature)
 	for _, paramStr := range paramStrings {
 		paramStr = strings.TrimSpace(paramStr)
 		if paramStr == "" {

ir/normalize.go

@@ -113,21 +113,40 @@ func normalizeDefaultValue(value string) string {
 	}
 
 	// Handle type casting - remove explicit type casts that are semantically equivalent
-	// Use regex to properly handle type casts within complex expressions
-	// Pattern: 'literal'::type -> 'literal' (removes redundant casts from string literals)
 	if strings.Contains(value, "::") {
-		// Use regex to match and remove type casts from string literals
-		// This handles: 'text'::text, 'utc'::text, '{}'::jsonb, '{}'::text[], etc.
-		// Also handles multi-word types like 'value'::character varying
+		// Handle NULL::type -> NULL
+		// Example: NULL::text -> NULL
+		re := regexp.MustCompile(`\bNULL::(?:[a-zA-Z_][\w\s.]*)(?:\[\])?`)
+		value = re.ReplaceAllString(value, "NULL")
+
+		// Handle numeric literals with type casts
+		// Example: '-1'::integer -> -1
+		// Example: '100'::bigint -> 100
+		// Note: PostgreSQL sometimes casts numeric literals to different types, e.g., -1::integer stored as numeric
+		re = regexp.MustCompile(`'(-?\d+(?:\.\d+)?)'::(?:integer|bigint|smallint|numeric|decimal|real|double precision|int2|int4|int8|float4|float8)`)
+		value = re.ReplaceAllString(value, "$1")
+
+		// Handle string literals with type casts (including escaped quotes)
+		// Example: 'text'::text -> 'text'
+		// Example: 'O''Brien'::text -> 'O''Brien'
+		// Example: '{}'::jsonb -> '{}'
+		// Example: '{1,2,3}'::integer[] -> '{1,2,3}'
 		// Pattern explanation:
-		// '([^']*)' - matches a quoted string literal (capturing the content)
+		// '(?:[^']|'')*' - matches a quoted string literal, handling escaped quotes ''
 		// ::[a-zA-Z_][\w\s.]* - matches ::typename
-		//   [a-zA-Z_] - type name must start with letter or underscore
-		//   [\w\s.]* - followed by word chars, spaces, or dots (for "character varying" or "pg_catalog.text")
-		// (?:\[\])? - optionally followed by [] for array types (non-capturing group)
-		// (?:\b|(?=\[)|$) - followed by word boundary, opening bracket, or end of string
-		re := regexp.MustCompile(`'([^']*)'::(?:[a-zA-Z_][\w\s.]*)(?:\[\])?`)
-		value = re.ReplaceAllString(value, "'$1'")
+		// (?:\[\])? - optionally followed by [] for array types
+		re = regexp.MustCompile(`('(?:[^']|'')*')::(?:[a-zA-Z_][\w\s.]*)(?:\[\])?`)
+		value = re.ReplaceAllString(value, "$1")
+
+		// Handle date/timestamp literals with type casts
+		// Example: '2024-01-01'::date -> '2024-01-01'
+		// Already handled by the string literal pattern above
+
+		// Handle parenthesized expressions with type casts - remove outer parentheses
+		// Example: (100)::bigint -> 100::bigint
+		// Pattern captures the number and the type cast separately
+		re = regexp.MustCompile(`\((\d+)\)(::(?:bigint|integer|smallint|numeric|decimal))`)
+		value = re.ReplaceAllString(value, "$1$2")
 	}
 
 	return value

testdata/diff/create_function/add_function/diff.sql

@@ -1,7 +1,11 @@
 CREATE OR REPLACE FUNCTION process_order(
     order_id integer,
     discount_percent numeric DEFAULT 0,
-    note varchar DEFAULT ''
+    priority_level integer DEFAULT 1,
+    note varchar DEFAULT '',
+    status text DEFAULT 'pending',
+    apply_tax boolean DEFAULT true,
+    is_priority boolean DEFAULT false
 )
 RETURNS numeric
 LANGUAGE plpgsql

testdata/diff/create_function/add_function/new.sql

@@ -1,7 +1,14 @@
 CREATE FUNCTION process_order(
     order_id integer,
+    -- Simple numeric defaults
     discount_percent numeric DEFAULT 0,
-    note varchar DEFAULT ''
+    priority_level integer DEFAULT 1,
+    -- String defaults
+    note varchar DEFAULT '',
+    status text DEFAULT 'pending',
+    -- Boolean defaults
+    apply_tax boolean DEFAULT true,
+    is_priority boolean DEFAULT false
 )
 RETURNS numeric
 LANGUAGE plpgsql

testdata/diff/create_function/add_function/plan.json

@@ -9,7 +9,7 @@
     {
       "steps": [
         {
-          "sql": "CREATE OR REPLACE FUNCTION process_order(\n    order_id integer,\n    discount_percent numeric DEFAULT 0,\n    note varchar DEFAULT ''\n)\nRETURNS numeric\nLANGUAGE plpgsql\nSECURITY DEFINER\nVOLATILE\nSTRICT\nAS $$\nDECLARE\n    total numeric;\nBEGIN\n    SELECT amount INTO total FROM orders WHERE id = order_id;\n    RETURN total - (total * discount_percent / 100);\nEND;\n$$;",
+          "sql": "CREATE OR REPLACE FUNCTION process_order(\n    order_id integer,\n    discount_percent numeric DEFAULT 0,\n    priority_level integer DEFAULT 1,\n    note varchar DEFAULT '',\n    status text DEFAULT 'pending',\n    apply_tax boolean DEFAULT true,\n    is_priority boolean DEFAULT false\n)\nRETURNS numeric\nLANGUAGE plpgsql\nSECURITY DEFINER\nVOLATILE\nSTRICT\nAS $$\nDECLARE\n    total numeric;\nBEGIN\n    SELECT amount INTO total FROM orders WHERE id = order_id;\n    RETURN total - (total * discount_percent / 100);\nEND;\n$$;",
           "type": "function",
           "operation": "create",
           "path": "public.process_order"

testdata/diff/create_function/add_function/plan.sql

@@ -1,7 +1,11 @@
 CREATE OR REPLACE FUNCTION process_order(
     order_id integer,
     discount_percent numeric DEFAULT 0,
-    note varchar DEFAULT ''
+    priority_level integer DEFAULT 1,
+    note varchar DEFAULT '',
+    status text DEFAULT 'pending',
+    apply_tax boolean DEFAULT true,
+    is_priority boolean DEFAULT false
 )
 RETURNS numeric
 LANGUAGE plpgsql

testdata/diff/create_function/add_function/plan.txt

@@ -12,7 +12,11 @@ DDL to be executed:
 CREATE OR REPLACE FUNCTION process_order(
     order_id integer,
     discount_percent numeric DEFAULT 0,
-    note varchar DEFAULT ''
+    priority_level integer DEFAULT 1,
+    note varchar DEFAULT '',
+    status text DEFAULT 'pending',
+    apply_tax boolean DEFAULT true,
+    is_priority boolean DEFAULT false
 )
 RETURNS numeric
 LANGUAGE plpgsql