diff --git a/src/schema2mock/generators/mock_generator.py b/src/schema2mock/generators/mock_generator.py
index 70705e7..43a195d 100644
--- a/src/schema2mock/generators/mock_generator.py
+++ b/src/schema2mock/generators/mock_generator.py
@@ -1 +1,480 @@
-read
\ No newline at end of file
+```python
+"""Mock data generator that respects JSON Schema constraints."""
+
+import random
+import re
+import string
+from dataclasses import dataclass
+from typing import Any, Callable, Dict, List, Optional
+
+from faker import Faker
+
+from schema2mock.core.schema_parser import SchemaParser
+
+
+@dataclass
+class GeneratorConfig:
+    """Configuration for mock data generation."""
+
+    locale: str = "en_US"
+    seed: Optional[int] = None
+    min_string_length: int = 1
+    max_string_length: int = 100
+    min_array_items: int = 1
+    max_array_items: int = 10
+    default_minimum: float = 0
+    default_maximum: float = 1000
+    null_probability: float = 0.0
+
+
+class MockGenerator:
+    """Generate realistic mock data from JSON Schema."""
+
+    FORMAT_MAPPING = {
+        "date-time": "date_time",
+        "date": "date",
+        "time": "time",
+        "email": "email",
+        "idn-email": "email",
+        "hostname": "hostname",
+        "idn-hostname": "hostname",
+        "ipv4": "ipv4",
+        "ipv6": "ipv6",
+        "uri": "uri",
+        "uri-reference": "uri",
+        "uuid": "uuid",
+    }
+
+    TYPE_MAPPING = {
+        "string": "text",
+        "number": "pyfloat",
+        "integer": "random_int",
+        "boolean": "boolean",
+        "array": "word",
+        "object": "pydict",
+        "null": "null_object",
+    }
+
+    def __init__(self, config: Optional[GeneratorConfig] = None):
+        self.config = config or GeneratorConfig()
+        self.faker = Faker(self.config.locale)
+        if self.config.seed is not None:
+            Faker.seed(self.config.seed)
+            random.seed(self.config.seed)
+        self._custom_providers: Dict[str, Callable] = {}
+
+    def register_provider(self, name: str, func: Callable) -> None:
+        """Register a custom Faker provider."""
+        self._custom_providers[name] = func
+
+    def generate(self, schema: Dict[str, Any]) -> Any:
+        """Generate mock data from a schema."""
+        if "$ref" in schema:
+            raise ValueError("Schema must be resolved before generation")
+
+        schema_type = schema.get("type")
+
+        if "const" in schema:
+            return schema["const"]
+
+        if "enum" in schema:
+            return self.generate_enum(schema["enum"])
+
+        if "allOf" in schema:
+            return self.handle_allof(schema["allOf"])
+
+        if "anyOf" in schema:
+            return self.handle_anyof(schema["anyOf"])
+
+        if "oneOf" in schema:
+            return self.handle_oneof(schema["oneOf"])
+
+        if "not" in schema:
+            return self.handle_not(schema["not"])
+
+        if schema_type is None:
+            if "properties" in schema:
+                schema_type = "object"
+            elif "items" in schema:
+                schema_type = "array"
+
+        if schema_type == "object":
+            return self.generate_object(schema)
+        elif schema_type == "array":
+            return self.generate_array(schema)
+        elif schema_type == "string":
+            return self.generate_string(schema)
+        elif schema_type == "number":
+            return self.generate_number(schema)
+        elif schema_type == "integer":
+            return self.generate_integer(schema)
+        elif schema_type == "boolean":
+            return self.generate_boolean(schema)
+        elif schema_type == "null":
+            return None
+        else:
+            return self.faker.word()
+
+    def generate_string(self, schema: Dict[str, Any]) -> str:
+        """Generate a string respecting constraints."""
+        constraints = schema.get("type") == "string" and schema or {**schema, "type": "string"}
+
+        min_length = constraints.get("minLength", self.config.min_string_length)
+        max_length = constraints.get("maxLength", self.config.max_string_length)
+        max_length = max(min_length, max_length)
+
+        pattern = constraints.get("pattern")
+        if pattern:
+            return self._generate_from_pattern(pattern, min_length, max_length)
+
+        format_type = constraints.get("format")
+        if format_type and format_type in self.FORMAT_MAPPING:
+            faker_method = self.FORMAT_MAPPING[format_type]
+            if hasattr(self.faker, faker_method):
+                result = getattr(self.faker, faker_method)()
+                if isinstance(result, str):
+                    if len(result) < min_length:
+                        result = result * ((min_length // len(result)) + 1)
+                    if len(result) > max_length:
+                        result = result[:max_length]
+                    return result
+
+        if format_type == "binary":
+            length = random.randint(min_length, max_length)
+            return "".join(random.choices(string.digits + string.ascii_letters, k=length))
+
+        if format_type == "byte":
+            length = random.randint(min_length, max_length)
+            return "".join(random.choices(string.ascii_letters + string.digits + "+/", k=length))
+
+        if format_type == "password":
+            length = random.randint(min_length, max_length)
+            return "".join(random.choices(string.ascii_letters + string.digits + "!@#$%^&*", k=length))
+
+        result = self.faker.text(max_nb_chars=max_length)
+        if len(result) < min_length:
+            result = result * ((min_length // len(result)) + 1)
+        return result[:max_length]
+
+    def _generate_from_pattern(self, pattern: str, min_length: int, max_length: int) -> str:
+        """Generate a string matching a regex pattern."""
+        try:
+            regex = re.compile(pattern)
+
+            if regex.pattern.startswith("^"):
+                regex = re.compile(regex.pattern.lstrip("^"))
+
+            if hasattr(regex, "pattern") and regex.pattern.endswith("$"):
+                regex = re.compile(regex.pattern.rstrip("$"))
+
+            if regex.pattern.startswith("[") and "]" in regex.pattern:
+                return self._generate_from_character_class(regex.pattern, min_length, max_length)
+
+            attempts = 0
+            max_attempts = 100
+            while attempts < max_attempts:
+                result = self._generate_from_regex_simple(pattern)
+                if result and min_length <= len(result) <= max_length:
+                    try:
+                        if regex.fullmatch(result):
+                            return result
+                    except re.error:
+                        pass
+                attempts += 1
+
+            return self._fallback_string(min_length, max_length)
+
+        except re.error:
+            return self._fallback_string(min_length, max_length)
+
+    def _generate_from_character_class(self, char_class: str, min_length: int, max_length: int) -> str:
+        """Generate a string from a character class pattern."""
+        char_class = char_class.lstrip("[").rstrip("]")
+
+        negated = False
+        if char_class.startswith("^"):
+            negated = True
+            char_class = char_class.lstrip("^")
+
+        chars = []
+        i = 0
+        while i < len(char_class):
+            if i + 2 < len(char_class) and char_class[i + 1] == "-":
+                start = ord(char_class[i])
+                end = ord(char_class[i + 2])
+                if start <= end:
+                    for c in range(start, end + 1):
+                        chars.append(chr(c))
+                i += 3
+            else:
+                chars.append(char_class[i])
+                i += 1
+
+        if negated:
+            all_chars = string.ascii_letters + string.digits
+            chars = [c for c in all_chars if c not in chars]
+
+        if not chars:
+            chars = ["a"]
+
+        length = random.randint(min_length, max_length)
+        return "".join(random.choice(chars) for _ in range(length))
+
+    def _generate_from_regex_simple(self, pattern: str) -> str:
+        """Simple regex pattern generation."""
+        result = ""
+        i = 0
+        while i < len(pattern):
+            if pattern[i] == "\\" and i + 1 < len(pattern):
+                escaped = pattern[i + 1]
+                if escaped == "d":
+                    result += random.choice(string.digits)
+                elif escaped == "w":
+                    result += random.choice(string.ascii_letters + string.digits)
+                elif escaped == "s":
+                    result += " "
+                elif escaped == "D":
+                    result += random.choice(string.ascii_letters)
+                elif escaped == "W":
+                    result += random.choice(string.punctuation)
+                else:
+                    result += escaped
+                i += 2
+            elif pattern[i] == "[":
+                end = pattern.find("]", i)
+                if end != -1:
+                    char_class = pattern[i:end + 1]
+                    result += self._generate_from_character_class(char_class, 1, 1)
+                    i = end + 1
+                else:
+                    result += pattern[i]
+                    i += 1
+            elif pattern[i] == "*":
+                if result:
+                    last_char = result[-1]
+                    count = random.randint(0, 3)
+                    result += last_char * count
+                i += 1
+            elif pattern[i] == "+":
+                if result:
+                    last_char = result[-1]
+                    count = random.randint(1, 3)
+                    result += last_char * count
+                i += 1
+            elif pattern[i] == "?":
+                if result and random.random() > 0.5:
+                    result = result[:-1]
+                i += 1
+            elif pattern[i] == "(":
+                end = pattern.find(")", i)
+                if end != -1:
+                    inner = pattern[i + 1:end]
+                    if "|" in inner:
+                        options = inner.split("|")
+                        result += random.choice(options)
+                    i = end + 1
+                else:
+                    i += 1
+            else:
+                result += pattern[i]
+                i += 1
+        return result
+
+    def _fallback_string(self, min_length: int, max_length: int) -> str:
+        """Generate a fallback string."""
+        length = random.randint(min_length, max_length)
+        return "".join(random.choices(string.ascii_letters + string.digits, k=length))
+
+    def generate_number(self, schema: Dict[str, Any]) -> float:
+        """Generate a number respecting constraints."""
+        minimum = schema.get("minimum", self.config.default_minimum)
+        maximum = schema.get("maximum", self.config.default_maximum)
+        exclusive_min = schema.get("exclusiveMinimum", minimum)
+        exclusive_max = schema.get("exclusiveMaximum", maximum)
+        multiple_of = schema.get("multipleOf")
+
+        if exclusive_min > minimum:
+            minimum = exclusive_min
+        if exclusive_max < maximum:
+            maximum = exclusive_max
+
+        result = random.uniform(minimum, maximum)
+
+        if multiple_of:
+            result = round(result / multiple_of) * multiple_of
+
+        return round(result, 10)
+
+    def generate_integer(self, schema: Dict[str, Any]) -> int:
+        """Generate an integer respecting constraints."""
+        minimum = schema.get("minimum", self.config.default_minimum)
+        maximum = schema.get("maximum", self.config.default_maximum)
+        exclusive_min = schema.get("exclusiveMinimum")
+        exclusive_max = schema.get("exclusiveMaximum")
+        multiple_of = schema.get("multipleOf")
+
+        if exclusive_min is not None:
+            minimum = exclusive_min + 1
+        if exclusive_max is not None:
+            maximum = exclusive_max - 1
+
+        result = random.randint(int(minimum), int(maximum))
+
+        if multiple_of:
+            result = round(result / multiple_of) * int(multiple_of)
+
+        return result
+
+    def generate_boolean(self, schema: Dict[str, Any]) -> bool:
+        """Generate a boolean value."""
+        return self.faker.boolean()
+
+    def generate_array(self, schema: Dict[str, Any]) -> List[Any]:
+        """Generate an array respecting constraints."""
+        items_schema = schema.get("items", {})
+        min_items = schema.get("minItems", self.config.min_array_items)
+        max_items = schema.get("maxItems", self.config.max_array_items)
+        max_items = max(min_items, max_items)
+        unique = schema.get("uniqueItems", False)
+
+        length = random.randint(min_items, max_items)
+
+        if "enum" in items_schema:
+            if unique:
+                values = list(set(items_schema["enum"]))
+                if len(values) >= length:
+                    return random.sample(values, length)
+                return values + random.choices(values, k=length - len(values))
+            return random.choices(items_schema["enum"], k=length)
+
+        results = []
+        for _ in range(length):
+            results.append(self.generate(items_schema))
+
+        if unique and len(results) > 1:
+            seen = set()
+            unique_results = []
+            for item in results:
+                item_key = str(item)
+                if item_key not in seen:
+                    seen.add(item_key)
+                    unique_results.append(item)
+            while len(unique_results) < length:
+                new_item = self.generate(items_schema)
+                item_key = str(new_item)
+                if item_key not in seen:
+                    seen.add(item_key)
+                    unique_results.append(new_item)
+            results = unique_results
+
+        return results
+
+    def generate_object(self, schema: Dict[str, Any]) -> Dict[str, Any]:
+        """Generate an object respecting constraints."""
+        properties = schema.get("properties", {})
+        required = schema.get("required", [])
+        additional_props = schema.get("additionalProperties", True)
+
+        result = {}
+
+        for prop_name, prop_schema in properties.items():
+            if prop_name in required or self._should_include_optional():
+                if prop_name in self._custom_providers:
+                    result[prop_name] = self._custom_providers[prop_name]()
+                else:
+                    result[prop_name] = self.generate(prop_schema)
+
+        if additional_props and isinstance(additional_props, dict):
+            pattern_props = schema.get("patternProperties", {})
+            for pattern, prop_schema in pattern_props.items():
+                pass
+
+        return result
+
+    def _should_include_optional(self, probability: float = 0.7) -> bool:
+        """Determine if an optional property should be included."""
+        return random.random() < probability
+
+    def generate_enum(self, enum_values: List[Any]) -> Any:
+        """Generate a value from an enum."""
+        return random.choice(enum_values)
+
+    def handle_allof(self, schemas: List[Dict[str, Any]]) -> Dict[str, Any]:
+        """Handle allOf composition by merging schemas."""
+        merged = {}
+        required = set()
+
+        for schema in schemas:
+            resolved = self._resolve_composition_schema(schema)
+
+            if "properties" in resolved:
+                merged.update(resolved["properties"])
+
+            if "required" in resolved:
+                required.update(resolved["required"])
+
+            if "enum" in resolved:
+                return self.generate(resolved)
+
+        result = {}
+        for prop_name, prop_schema in merged.items():
+            if prop_name in required or self._should_include_optional():
+                result[prop_name] = self.generate(prop_schema)
+
+        return result
+
+    def handle_anyof(self, schemas: List[Dict[str, Any]]) -> Any:
+        """Handle anyOf composition by randomly selecting one branch."""
+        schema = random.choice(schemas)
+        resolved = self._resolve_composition_schema(schema)
+        return self.generate(resolved)
+
+    def handle_oneof(self, schemas: List[Dict[str, Any]]) -> Any:
+        """Handle oneOf composition (same as anyOf for generation)."""
+        return self.handle_anyof(schemas)
+
+    def handle_not(self, schema: Dict[str, Any]) -> Any:
+        """Handle not composition."""
+        return self.generate(schema)
+
+    def _resolve_composition_schema(self, schema: Dict[str, Any]) -> Dict[str, Any]:
+        """Resolve a schema that may contain references."""
+        if "$ref" in schema:
+            raise ValueError("Schema must be resolved before generation")
+        return schema
+
+    def generate_from_parser(self, parser: SchemaParser) -> List[Dict[str, Any]]:
+        """Generate mock data from a parsed schema."""
+        parsed = parser.parse()
+
+        if isinstance(parsed, dict) and "operations" in parsed:
+            results = []
+            for op in parsed["operations"]:
+                mock_data = self.generate_operation(op, parser)
+                results.append({
+                    "path": op.get("path"),
+                    "method": op.get("method"),
+                    "operationId": op.get("operationId"),
+                    "mock_data": mock_data
+                })
+            return results
+        else:
+            return [self.generate(parsed)]
+
+    def generate_operation(self, operation: Dict[str, Any], parser: SchemaParser) -> Dict[str, Any]:
+        """Generate mock data for an OpenAPI operation."""
+        responses = operation.get("responses", {})
+
+        response_200 = responses.get("200") or responses.get("201") or responses.get("default")
+        if not response_200:
+            for status in ["200", "201", "202", "204"]:
+                if status in responses:
+                    response_200 = responses[status]
+                    break
+
+        if response_200 and response_200.get("schema"):
+            schema = parser.resolve_schema(response_200["schema"])
+            return self.generate(schema)
+
+        return {"message": "No schema available for this operation"}
+```
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