package dynamodb

import "core:fmt"
import "core:strings"

// DynamoDB AttributeValue - the core data type
Attribute_Value :: union {
	String,         // S
	DDB_Number,     // N — decimal-preserving numeric type
	Binary,         // B (base64)
	Bool,           // BOOL
	Null,           // NULL
	String_Set,     // SS
	DDB_Number_Set, // NS
	Binary_Set,     // BS
	List,           // L
	Map,            // M
}

String :: distinct string
Binary :: distinct string
Bool :: distinct bool
Null :: distinct bool

String_Set :: distinct []string
DDB_Number_Set :: distinct []DDB_Number
Binary_Set :: distinct []string
List :: distinct []Attribute_Value
Map :: distinct map[string]Attribute_Value

// Item is a map of attribute names to values
Item :: map[string]Attribute_Value

// Key represents a DynamoDB key (partition key + optional sort key)
Key :: struct {
	pk: Attribute_Value,
	sk: Maybe(Attribute_Value),
}

// Free a key
key_destroy :: proc(key: ^Key) {
	attr_value_destroy(&key.pk)
	if sk, ok := key.sk.?; ok {
		sk_copy := sk
		attr_value_destroy(&sk_copy)
	}
}

// Extract key from item based on key schema
key_from_item :: proc(item: Item, key_schema: []Key_Schema_Element) -> (Key, bool) {
	pk_value: Attribute_Value
	sk_value: Maybe(Attribute_Value)

	for schema_elem in key_schema {
		attr, ok := item[schema_elem.attribute_name]
		if !ok {
			return {}, false
		}

		// Validate that key is a scalar type (S, N, or B)
		#partial switch _ in attr {
		case String, DDB_Number, Binary:
			// Valid key type
		case:
			return {}, false
		}

		// Deep copy the attribute value
		copied := attr_value_deep_copy(attr)

		switch schema_elem.key_type {
		case .HASH:
			pk_value = copied
		case .RANGE:
			sk_value = copied
		}
	}

	return Key{pk = pk_value, sk = sk_value}, true
}

// Convert key to item
key_to_item :: proc(key: Key, key_schema: []Key_Schema_Element) -> Item {
	item := make(Item)

	for schema_elem in key_schema {
		attr_value: Attribute_Value

		switch schema_elem.key_type {
		case .HASH:
			attr_value = key.pk
		case .RANGE:
			if sk, ok := key.sk.?; ok {
				attr_value = sk
			} else {
				continue
			}
		}

		item[schema_elem.attribute_name] = attr_value_deep_copy(attr_value)
	}

	return item
}

// Extract raw byte values from key
Key_Values :: struct {
	pk: []byte,
	sk: Maybe([]byte),
}

key_get_values :: proc(key: ^Key) -> (Key_Values, bool) {
	pk_bytes: []byte

	#partial switch v in key.pk {
	case String:
		pk_bytes = transmute([]byte)string(v)
	case DDB_Number:
		pk_bytes = encode_ddb_number_for_sort(v)
	case Binary:
		pk_bytes = transmute([]byte)string(v)
	case:
		return {}, false
	}

	sk_bytes: Maybe([]byte)
	if sk, ok := key.sk.?; ok {
		#partial switch v in sk {
		case String:
			sk_bytes = transmute([]byte)string(v)
		case DDB_Number:
			sk_bytes = encode_ddb_number_for_sort(v)
		case Binary:
			sk_bytes = transmute([]byte)string(v)
		case:
			return {}, false
		}
	}

	return Key_Values{pk = pk_bytes, sk = sk_bytes}, true
}

// Key type
Key_Type :: enum {
	HASH,
	RANGE,
}

key_type_to_string :: proc(kt: Key_Type) -> string {
	switch kt {
	case .HASH:  return "HASH"
	case .RANGE: return "RANGE"
	}
	return "HASH"
}

key_type_from_string :: proc(s: string) -> (Key_Type, bool) {
	switch s {
	case "HASH":  return .HASH, true
	case "RANGE": return .RANGE, true
	}
	return .HASH, false
}

// Scalar attribute type
Scalar_Attribute_Type :: enum {
	S, // String
	N, // Number
	B, // Binary
}

scalar_type_to_string :: proc(t: Scalar_Attribute_Type) -> string {
	switch t {
	case .S: return "S"
	case .N: return "N"
	case .B: return "B"
	}
	return "S"
}

scalar_type_from_string :: proc(s: string) -> (Scalar_Attribute_Type, bool) {
	switch s {
	case "S": return .S, true
	case "N": return .N, true
	case "B": return .B, true
	}
	return .S, false
}

// Key schema element
Key_Schema_Element :: struct {
	attribute_name: string,
	key_type:       Key_Type,
}

// Attribute definition
Attribute_Definition :: struct {
	attribute_name: string,
	attribute_type: Scalar_Attribute_Type,
}

// Projection type for indexes
Projection_Type :: enum {
	ALL,
	KEYS_ONLY,
	INCLUDE,
}

// Projection
Projection :: struct {
	projection_type:     Projection_Type,
	non_key_attributes:  Maybe([]string),
}

// Global secondary index
Global_Secondary_Index :: struct {
	index_name:  string,
	key_schema:  []Key_Schema_Element,
	projection:  Projection,
}

// Local secondary index
Local_Secondary_Index :: struct {
	index_name:  string,
	key_schema:  []Key_Schema_Element,
	projection:  Projection,
}

// Table status
Table_Status :: enum {
	CREATING,
	UPDATING,
	DELETING,
	ACTIVE,
	INACCESSIBLE_ENCRYPTION_CREDENTIALS,
	ARCHIVING,
	ARCHIVED,
}

table_status_to_string :: proc(status: Table_Status) -> string {
	switch status {
	case .CREATING: return "CREATING"
	case .UPDATING: return "UPDATING"
	case .DELETING: return "DELETING"
	case .ACTIVE:   return "ACTIVE"
	case .INACCESSIBLE_ENCRYPTION_CREDENTIALS: return "INACCESSIBLE_ENCRYPTION_CREDENTIALS"
	case .ARCHIVING: return "ARCHIVING"
	case .ARCHIVED:  return "ARCHIVED"
	}
	return "ACTIVE"
}

table_status_from_string :: proc(s: string) -> Table_Status {
	switch s {
	case "CREATING": return .CREATING
	case "UPDATING": return .UPDATING
	case "DELETING": return .DELETING
	case "ACTIVE":   return .ACTIVE
	case "ARCHIVING": return .ARCHIVING
	case "ARCHIVED":  return .ARCHIVED
	}
	return .ACTIVE
}

// Table description
Table_Description :: struct {
	table_name:                 string,
	key_schema:                 []Key_Schema_Element,
	attribute_definitions:      []Attribute_Definition,
	table_status:               Table_Status,
	creation_date_time:         i64,
	item_count:                 u64,
	table_size_bytes:           u64,
	global_secondary_indexes:   Maybe([]Global_Secondary_Index),
	local_secondary_indexes:    Maybe([]Local_Secondary_Index),
}

// DynamoDB operation types
Operation :: enum {
	CreateTable,
	DeleteTable,
	DescribeTable,
	ListTables,
	UpdateTable,
	PutItem,
	GetItem,
	DeleteItem,
	UpdateItem,
	Query,
	Scan,
	BatchGetItem,
	BatchWriteItem,
	TransactGetItems,
	TransactWriteItems,
	Unknown,
}

operation_from_target :: proc(target: string) -> Operation {
	prefix :: "DynamoDB_20120810."
	if !strings.has_prefix(target, prefix) {
		return .Unknown
	}

	op_name := target[len(prefix):]

	switch op_name {
	case "CreateTable":      return .CreateTable
	case "DeleteTable":      return .DeleteTable
	case "DescribeTable":    return .DescribeTable
	case "ListTables":       return .ListTables
	case "UpdateTable":      return .UpdateTable
	case "PutItem":          return .PutItem
	case "GetItem":          return .GetItem
	case "DeleteItem":       return .DeleteItem
	case "UpdateItem":       return .UpdateItem
	case "Query":            return .Query
	case "Scan":             return .Scan
	case "BatchGetItem":     return .BatchGetItem
	case "BatchWriteItem":   return .BatchWriteItem
	case "TransactGetItems": return .TransactGetItems
	case "TransactWriteItems": return .TransactWriteItems
	}

	return .Unknown
}

// DynamoDB error types
DynamoDB_Error_Type :: enum {
	ValidationException,
	ResourceNotFoundException,
	ResourceInUseException,
	ConditionalCheckFailedException,
	ProvisionedThroughputExceededException,
	ItemCollectionSizeLimitExceededException,
	InternalServerError,
	SerializationException,
}

error_to_response :: proc(err_type: DynamoDB_Error_Type, message: string) -> string {
	type_str: string

	switch err_type {
	case .ValidationException:
		type_str = "com.amazonaws.dynamodb.v20120810#ValidationException"
	case .ResourceNotFoundException:
		type_str = "com.amazonaws.dynamodb.v20120810#ResourceNotFoundException"
	case .ResourceInUseException:
		type_str = "com.amazonaws.dynamodb.v20120810#ResourceInUseException"
	case .ConditionalCheckFailedException:
		type_str = "com.amazonaws.dynamodb.v20120810#ConditionalCheckFailedException"
	case .ProvisionedThroughputExceededException:
		type_str = "com.amazonaws.dynamodb.v20120810#ProvisionedThroughputExceededException"
	case .ItemCollectionSizeLimitExceededException:
		type_str = "com.amazonaws.dynamodb.v20120810#ItemCollectionSizeLimitExceededException"
	case .InternalServerError:
		type_str = "com.amazonaws.dynamodb.v20120810#InternalServerError"
	case .SerializationException:
		type_str = "com.amazonaws.dynamodb.v20120810#SerializationException"
	}

	return fmt.aprintf(`{{"__type":"%s","message":"%s"}}`, type_str, message)
}

// Build an Attribute_Value with the correct scalar type from raw bytes
build_attribute_value_with_type :: proc(raw_bytes: []byte, attr_type: Scalar_Attribute_Type) -> Attribute_Value {
	switch attr_type {
	case .S:
		return String(strings.clone(string(raw_bytes)))
	case .N:
		// Key bytes are canonical-encoded via encode_ddb_number_for_sort.
		// Decode them back to a DDB_Number.
		ddb_num, ok := decode_ddb_number_from_sort(raw_bytes)
		if ok {
			return clone_ddb_number(ddb_num)
		}
		// Fallback: try interpreting as a plain numeric string
		fallback_num, fb_ok := parse_ddb_number(string(raw_bytes))
		if fb_ok {
			return fallback_num
		}
		// Last resort — return as string (shouldn't happen)
		return String(strings.clone(string(raw_bytes)))
	case .B:
		return Binary(strings.clone(string(raw_bytes)))
	}
	return String(strings.clone(string(raw_bytes)))
}

// Deep copy an attribute value
attr_value_deep_copy :: proc(attr: Attribute_Value) -> Attribute_Value {
	switch v in attr {
	case String:
		return String(strings.clone(string(v)))
	case DDB_Number:
		return clone_ddb_number(v)
	case Binary:
		return Binary(strings.clone(string(v)))
	case Bool:
		return v
	case Null:
		return v
	case String_Set:
		ss := make([]string, len(v))
		for s, i in v {
			ss[i] = strings.clone(s)
		}
		return String_Set(ss)
	case DDB_Number_Set:
		ddb_ns := make([]DDB_Number, len(v))
		for num, i in v {
			ddb_ns[i] = clone_ddb_number(num)
		}
		return DDB_Number_Set(ddb_ns)
	case Binary_Set:
		bs := make([]string, len(v))
		for b, i in v {
			bs[i] = strings.clone(b)
		}
		return Binary_Set(bs)
	case List:
		list := make([]Attribute_Value, len(v))
		for item, i in v {
			list[i] = attr_value_deep_copy(item)
		}
		return List(list)
	case Map:
		m := make(map[string]Attribute_Value)
		for key, val in v {
			m[strings.clone(key)] = attr_value_deep_copy(val)
		}
		return Map(m)
	}
	return nil
}

// Free an attribute value
attr_value_destroy :: proc(attr: ^Attribute_Value) {
	switch v in attr {
	case String:
		delete(string(v))
	case DDB_Number:
		delete(v.integer_part)
		delete(v.fractional_part)
	case Binary:
		delete(string(v))
	case String_Set:
		for s in v {
			delete(s)
		}
		slice := v
		delete(slice)
	case DDB_Number_Set:
		for num in v {
			delete(num.integer_part)
			delete(num.fractional_part)
		}
		delete(v)
	case Binary_Set:
		for b in v {
			delete(b)
		}
		slice := v
		delete(slice)
	case List:
		for item in v {
			item_copy := item
			attr_value_destroy(&item_copy)
		}
		list := v
		delete(list)
	case Map:
		for key, val in v {
			delete(key)
			val_copy := val
			attr_value_destroy(&val_copy)
		}
		m := v
		delete(m)
	case Bool, Null:
		// Nothing to free
	}
}

// Free an item
item_destroy :: proc(item: ^Item) {
	for key, val in item {
		delete(key)
		val_copy := val
		attr_value_destroy(&val_copy)
	}
	delete(item^)
}