// Copyright 2016-2017, Pulumi Corporation.  All rights reserved.

package diag

// ID is a unique diagnostics identifier.
type ID int

// Diag is an instance of an error or warning generated by the compiler.
type Diag struct {
	ID      ID        // a unique identifier for this diagnostic.
	Message string    // a human-friendly message for this diagnostic.
	Doc     *Document // the document in which this diagnostic occurred.
	Loc     *Location // the document location at which this diagnostic occurred.
}

// Message returns an anonymous diagnostic message without any source or ID information.
func Message(msg string) *Diag {
	return &Diag{Message: msg}
}

// Diagable can be used to determine a diagnostic's position.
type Diagable interface {
	Where() (*Document, *Location)
}

// At adds a position to an existing diagnostic, retaining its ID and message.
func (diag *Diag) At(d Diagable) *Diag {
	var doc *Document
	var loc *Location
	if d != nil {
		doc, loc = d.Where()
	}
	return &Diag{
		ID:      diag.ID,
		Message: diag.Message,
		Doc:     doc,
		Loc:     loc,
	}
}

// AtFile adds a file to an existing diagnostic, retaining its ID and message.
func (diag *Diag) AtFile(file string) *Diag {
	return &Diag{
		ID:      diag.ID,
		Message: diag.Message,
		Doc:     NewDocument(file),
	}
}