// Copyright 2019 The Go Authors. All rights reserved.

// Use of this source code is governed by a BSD-style

// license that can be found in the LICENSE file.

package protoreflect

import (

	"strconv"

)

// SourceLocations is a list of source locations.

type SourceLocations interface {

	// Len reports the number of source locations in the proto file.

	Len() int

	// Get returns the ith SourceLocation. It panics if out of bounds.

	Get(int) SourceLocation

	// ByPath returns the SourceLocation for the given path,

	// returning the first location if multiple exist for the same path.

	// If multiple locations exist for the same path,

	// then SourceLocation.Next index can be used to identify the

	// index of the next SourceLocation.

	// If no location exists for this path, it returns the zero value.

	ByPath(path SourcePath) SourceLocation

	// ByDescriptor returns the SourceLocation for the given descriptor,

	// returning the first location if multiple exist for the same path.

	// If no location exists for this descriptor, it returns the zero value.

	ByDescriptor(desc Descriptor) SourceLocation

	doNotImplement

}

// SourceLocation describes a source location and

// corresponds with the google.protobuf.SourceCodeInfo.Location message.

type SourceLocation struct {

	// Path is the path to the declaration from the root file descriptor.

	// The contents of this slice must not be mutated.

	Path SourcePath

	// StartLine and StartColumn are the zero-indexed starting location

	// in the source file for the declaration.

	StartLine, StartColumn int

	// EndLine and EndColumn are the zero-indexed ending location

	// in the source file for the declaration.

	// In the descriptor.proto, the end line may be omitted if it is identical

	// to the start line. Here, it is always populated.

	EndLine, EndColumn int

	// LeadingDetachedComments are the leading detached comments

	// for the declaration. The contents of this slice must not be mutated.

	LeadingDetachedComments []string

	// LeadingComments is the leading attached comment for the declaration.

	LeadingComments string

	// TrailingComments is the trailing attached comment for the declaration.

	TrailingComments string

	// Next is an index into SourceLocations for the next source location that

	// has the same Path. It is zero if there is no next location.

	Next int

}

// SourcePath identifies part of a file descriptor for a source location.

// The SourcePath is a sequence of either field numbers or indexes into

// a repeated field that form a path starting from the root file descriptor.

//

// See google.protobuf.SourceCodeInfo.Location.path.

type SourcePath []int32

// Equal reports whether p1 equals p2.

func (p1 SourcePath) Equal(p2 SourcePath) bool {

	if len(p1) != len(p2) {

		return false

	}

	for i := range p1 {

		if p1[i] != p2[i] {

			return false

		}

	}

	return true

}

// String formats the path in a humanly readable manner.

// The output is guaranteed to be deterministic,

// making it suitable for use as a key into a Go map.

// It is not guaranteed to be stable as the exact output could change

// in a future version of this module.

//

// Example output:

//	.message_type[6].nested_type[15].field[3]

func (p SourcePath) String() string {

	b := p.appendFileDescriptorProto(nil)

	for _, i := range p {

		b = append(b, '.')

		b = strconv.AppendInt(b, int64(i), 10)

	}

	return string(b)

}

type appendFunc func(*SourcePath, []byte) []byte

func (p *SourcePath) appendSingularField(b []byte, name string, f appendFunc) []byte {

	if len(*p) == 0 {

		return b

	}

	b = append(b, '.')

	b = append(b, name...)

	*p = (*p)[1:]

	if f != nil {

		b = f(p, b)

	}

	return b

}

func (p *SourcePath) appendRepeatedField(b []byte, name string, f appendFunc) []byte {

	b = p.appendSingularField(b, name, nil)

	if len(*p) == 0 || (*p)[0] < 0 {

		return b

	}

	b = append(b, '[')

	b = strconv.AppendUint(b, uint64((*p)[0]), 10)

	b = append(b, ']')

	*p = (*p)[1:]

	if f != nil {

		b = f(p, b)

	}

	return b

}