package cover

import (
	"crypto/sha256"
	"fmt"
	"path"

	"github.com/qiniu/goc/v2/pkg/config"
)

// declareCoverVars attaches the required cover variables names
// to the files, to be used when annotating the files.
func declareCoverVars(p *config.Package) map[string]*config.FileVar {
	coverVars := make(map[string]*config.FileVar)
	coverIndex := 0
	// We create the cover counters as new top-level variables in the package.
	// We need to avoid collisions with user variables (GoCover_0 is unlikely but still)
	// and more importantly with dot imports of other covered packages,
	// so we append 12 hex digits from the SHA-256 of the import path.
	// The point is only to avoid accidents, not to defeat users determined to
	// break things.
	sum := sha256.Sum256([]byte(p.ImportPath))
	h := fmt.Sprintf("%x", sum[:6])
	for _, file := range p.GoFiles {
		// These names appear in the cmd/cover HTML interface.
		var longFile = path.Join(p.ImportPath, file)
		coverVars[file] = &config.FileVar{
			File: longFile,
			Var:  fmt.Sprintf("GoCover_%d_%x", coverIndex, h),
		}
		coverIndex++
	}

	for _, file := range p.CgoFiles {
		// These names appear in the cmd/cover HTML interface.
		var longFile = path.Join(p.ImportPath, file)
		coverVars[file] = &config.FileVar{
			File: longFile,
			Var:  fmt.Sprintf("GoCover_%d_%x", coverIndex, h),
		}
		coverIndex++
	}

	return coverVars
}