package filepb

import (
	"errors"
	"fmt"

	"google.golang.org/protobuf/proto"
	"google.golang.org/protobuf/reflect/protoreflect"
)

var ErrProtoNoVarName error = errors.New("name not in .proto")
var ErrProtoVarNotString error = errors.New("name exists but is not a string")

// Gemini AI can help author some pretty good protobuf code.
// I never remember the syntax for 'reflect' on these things.

// sets "Filename" if it exists in the protobuf
func SetFilename(pb proto.Message, filename string) (bool, error) {
	msg := pb.ProtoReflect() // This is the entry point to the reflection API.

	descriptor := msg.Descriptor() // Get the message's descriptor, which contains metadata about its fields.

	fieldName := protoreflect.Name("Filename")
	fieldDescriptor := descriptor.Fields().ByName(fieldName)

	if fieldDescriptor == nil {
		fieldName = protoreflect.Name("filename")
		fieldDescriptor = descriptor.Fields().ByName(fieldName)
	}

	if fieldDescriptor == nil {
		return false, fmt.Errorf("fieldDescriptor == nil")
	}

	if fieldDescriptor.Kind() != protoreflect.StringKind {
		// The field exists but is not a string, so we can't return it as one.
		return false, fmt.Errorf("The field exists but is not a string")
	}

	valueToSet := protoreflect.ValueOfString(filename)

	// 6. If the field exists and is a string, get its value.
	// The value is returned as a protoreflect.Value.
	msg.Set(fieldDescriptor, valueToSet)

	// 7. Convert the protoreflect.Value to a native Go string.
	return true, nil
}

// this will try both "filename" and "Filename"
func GetFilename(pb proto.Message) (string, error) {
	// 1. Get the protoreflect.Message interface from the message.
	// This is the entry point to the reflection API.
	msg := pb.ProtoReflect()

	// 2. Get the message's descriptor, which contains metadata about its fields.
	descriptor := msg.Descriptor()

	// 3. Find the specific field descriptor by its protobuf name ("Filename").
	// Note: The field name must match the name in the .proto file.
	fieldName := protoreflect.Name("Filename")
	fieldDescriptor := descriptor.Fields().ByName(fieldName)

	// try upper case
	if fieldDescriptor == nil {
		fieldName = protoreflect.Name("filename")
		fieldDescriptor = descriptor.Fields().ByName(fieldName)
		// if fieldDescriptor == nil {
		// panic(".proto file: try 'Filename', not 'filename'? or maybe nomutex if pb.Marshal() fails")
		// }
	}

	// 4. Check if the field was found. If not, return false.
	if fieldDescriptor == nil {
		return "", ErrProtoNoVarName
	}

	// 5. (Optional but recommended) Verify the field is a string type.
	if fieldDescriptor.Kind() != protoreflect.StringKind {
		// The field exists but is not a string, so we can't return it as one.
		return "", ErrProtoVarNotString
	}

	// 6. If the field exists and is a string, get its value.
	// The value is returned as a protoreflect.Value.
	value := msg.Get(fieldDescriptor)

	// 7. Convert the protoreflect.Value to a native Go string.
	return value.String(), nil
}

// this will try both "filename" and "Filename"
func GetString(pb proto.Message, varname string) (string, error) {
	// 1. Get the protoreflect.Message interface from the message.
	// This is the entry point to the reflection API.
	msg := pb.ProtoReflect()

	// 2. Get the message's descriptor, which contains metadata about its fields.
	descriptor := msg.Descriptor()

	// 3. Find the specific field descriptor by its protobuf name ("Filename").
	// Note: The field name must match the name in the .proto file.
	fieldName := protoreflect.Name(varname)
	fieldDescriptor := descriptor.Fields().ByName(fieldName)

	// 4. Check if the field was found. If not, return false.
	if fieldDescriptor == nil {
		return "", ErrProtoNoVarName
	}

	// 5. (Optional but recommended) Verify the field is a string type.
	if fieldDescriptor.Kind() != protoreflect.StringKind {
		// The field exists but is not a string, so we can't return it as one.
		return "", ErrProtoVarNotString
	}

	// 6. If the field exists and is a string, get its value.
	// The value is returned as a protoreflect.Value.
	value := msg.Get(fieldDescriptor)

	// 7. Convert the protoreflect.Value to a native Go string.
	return value.String(), nil
}

// don't do this. use prototext.Format(pb)
// duh. I'm dumb. I literally wasted my time + was being lazy so I
// just asked asking Gemini AI to make some function for this
// when, for years, I use prototext.Format() all over the place
func printStrings(pb proto.Message) {
	// 1. Get the protoreflect.Message interface.
	msg := pb.ProtoReflect()

	// It's good practice to check if the message is valid.
	if !msg.IsValid() {
		fmt.Printf("Error: Provided protobuf message is not valid.")
		return
	}

	// 2. Get the message's descriptor.
	descriptor := msg.Descriptor()
	fmt.Printf("--- Listing String Fields in [%s] ---\n", descriptor.FullName())

	// 3. Get the collection of all field descriptors for this message.
	fields := descriptor.Fields()

	// 4. Iterate over all the fields.
	for i := 0; i < fields.Len(); i++ {
		// Get the descriptor for the field at the current index.
		fieldDescriptor := fields.Get(i)

		// 5. Check if the field's kind is a string.
		if fieldDescriptor.Kind() == protoreflect.StringKind {
			// 6. If it is a string, get its name and value.
			fieldName := fieldDescriptor.Name()
			value := msg.Get(fieldDescriptor).String()

			// 7. Print the formatted result.
			// We add a check to see if the field is populated. An empty string
			// is a valid value, but you might only want to see set fields.
			if msg.Has(fieldDescriptor) {
				fmt.Printf("  %s: \"%s\"\n", fieldName, value)
			}
		}
	}
}