Introduce NewContext to validate CLI flags

aswinkarthik · Oct 8, 2019 · 36438e4 · 36438e4
1 parent 037f723
commit 36438e4
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Showing 6 changed files with 396 additions and 244 deletions.
diff --git a/cmd/config.go b/cmd/config.go
@@ -12,50 +12,107 @@ import (
 
 // Context is to store all command line Flags.
 type Context struct {
-	PrimaryKeyPositions    []int
-	ValueColumnPositions   []int
-	IncludeColumnPositions []int
-	Format                 string
-	BaseFilename           string
-	DeltaFilename          string
+	fs                     afero.Fs
+	primaryKeyPositions    []int
+	valueColumnPositions   []int
+	includeColumnPositions []int
+	format                 string
+	baseFilename           string
+	deltaFilename          string
 	baseFile               afero.File
 	deltaFile              afero.File
+	recordCount            int
+}
+
+// NewContext can take all CLI flags and create a cmd.Context
+// Validations are done as part of this.
+// File pointers are created too.
+func NewContext(
+	fs afero.Fs,
+	primaryKeyPositions []int,
+	valueColumnPositions []int,
+	ignoreValueColumnPositions []int,
+	includeColumnPositions []int,
+	format string,
+	baseFilename string,
+	deltaFilename string,
+) (*Context, error) {
+	baseRecordCount, err := getColumnsCount(fs, baseFilename)
+	if err != nil {
+		return nil, fmt.Errorf("error in base-file: %v", err)
+	}
+
+	deltaRecordCount, err := getColumnsCount(fs, deltaFilename)
+	if err != nil {
+		return nil, fmt.Errorf("error in delta-file: %v", err)
+	}
+
+	if baseRecordCount != deltaRecordCount {
+		return nil, fmt.Errorf("base-file and delta-file columns count do not match")
+	}
+
+	baseFile, err := fs.Open(baseFilename)
+	if err != nil {
+		return nil, err
+	}
+	deltaFile, err := fs.Open(deltaFilename)
+	if err != nil {
+		return nil, err
+	}
+	ctx := &Context{
+		fs:                     fs,
+		primaryKeyPositions:    primaryKeyPositions,
+		valueColumnPositions:   valueColumnPositions,
+		includeColumnPositions: includeColumnPositions,
+		format:                 format,
+		baseFilename:           baseFilename,
+		deltaFilename:          deltaFilename,
+		baseFile:               baseFile,
+		deltaFile:              deltaFile,
+		recordCount:            baseRecordCount,
+	}
+
+	if err := ctx.validate(); err != nil {
+		return nil, fmt.Errorf("validation failed: %v", err)
+	}
+
+	return ctx, nil
 }
 
 // GetPrimaryKeys is to return the --primary-key flags as digest.Positions array.
 func (c *Context) GetPrimaryKeys() digest.Positions {
-	if len(c.PrimaryKeyPositions) > 0 {
-		return c.PrimaryKeyPositions
+	if len(c.primaryKeyPositions) > 0 {
+		return c.primaryKeyPositions
 	}
 	return []int{0}
 }
 
 // GetValueColumns is to return the --columns flags as digest.Positions array.
 func (c *Context) GetValueColumns() digest.Positions {
-	if len(c.ValueColumnPositions) > 0 {
-		return c.ValueColumnPositions
+	if len(c.valueColumnPositions) > 0 {
+		return c.valueColumnPositions
 	}
 	return []int{}
 }
 
 // GetIncludeColumnPositions is to return the --include flags as digest.Positions array.
 // If empty, it is value columns
 func (c Context) GetIncludeColumnPositions() digest.Positions {
-	if len(c.IncludeColumnPositions) > 0 {
-		return c.IncludeColumnPositions
+	if len(c.includeColumnPositions) > 0 {
+		return c.includeColumnPositions
 	}
 	return c.GetValueColumns()
 }
 
-// Validate validates the context object
+// validate validates the context object
 // and returns error if not valid.
-func (c *Context) Validate(fs afero.Fs) error {
+func (c *Context) validate() error {
 	{
 		// format validation
 
 		formatFound := false
 		for _, format := range allFormats {
-			if strings.ToLower(c.Format) == format {
+			if strings.ToLower(c.format) == format {
 				formatFound = true
 			}
 		}
@@ -65,62 +122,17 @@ func (c *Context) Validate(fs afero.Fs) error {
 	}
 
 	{
-		// base-file validation
-
-		if exists, err := afero.Exists(fs, c.BaseFilename); err != nil {
-			return fmt.Errorf("error reading base-file %s: %v", c.BaseFilename, err)
-		} else if !exists {
-			return fmt.Errorf("base-file %s does not exits", c.BaseFilename)
-		}
-
-		if isDir, err := afero.IsDir(fs, c.BaseFilename); err != nil {
-			return fmt.Errorf("error reading base-file %s: %v", c.BaseFilename, err)
-		} else if isDir {
-			return fmt.Errorf("base-file %s should be a file", c.BaseFilename)
-		}
-	}
-
-	{
-		// delta file validation
-
-		if exists, err := afero.Exists(fs, c.DeltaFilename); err != nil {
-			return fmt.Errorf("error reading delta-file %s: %v", c.DeltaFilename, err)
-		} else if !exists {
-			return fmt.Errorf("delta-file %s does not exits", c.DeltaFilename)
-		}
-
-		if isDir, err := afero.IsDir(fs, c.DeltaFilename); err != nil {
-			return fmt.Errorf("error reading delta-file %s: %v", c.DeltaFilename, err)
-		} else if isDir {
-			return fmt.Errorf("delta-file %s should be a file", c.DeltaFilename)
-		}
-	}
-
-	{
-		baseRecordCount, err := getColumnsCount(fs, c.BaseFilename)
-		if err != nil {
-			return err
-		}
-		deltaRecordCount, err := getColumnsCount(fs, c.DeltaFilename)
-		if err != nil {
-			return err
-		}
-
-		if baseRecordCount != deltaRecordCount {
-			return fmt.Errorf("base-file and delta-file columns count do not match")
-		}
-
 		comparator := func(element int) bool {
-			return element < baseRecordCount
+			return element < c.recordCount
 		}
 
-		if !assertAll(c.PrimaryKeyPositions, comparator) {
+		if !assertAll(c.primaryKeyPositions, comparator) {
 			return fmt.Errorf("--primary-key positions are out of bounds")
 		}
-		if !assertAll(c.IncludeColumnPositions, comparator) {
+		if !assertAll(c.includeColumnPositions, comparator) {
 			return fmt.Errorf("--include positions are out of bounds")
 		}
-		if !assertAll(c.ValueColumnPositions, comparator) {
+		if !assertAll(c.valueColumnPositions, comparator) {
 			return fmt.Errorf("--columns positions are out of bounds")
 		}
 	}
@@ -148,7 +160,7 @@ func getColumnsCount(fs afero.Fs, filename string) (int, error) {
 	record, err := csvReader.Read()
 	if err != nil {
 		if err == io.EOF {
-			return 0, fmt.Errorf("unable to process headers from csv file. EOF reached")
+			return 0, fmt.Errorf("unable to process headers from csv file. EOF reached. invalid CSV file")
 		}
 		return 0, err
 	}
@@ -158,37 +170,23 @@ func getColumnsCount(fs afero.Fs, filename string) (int, error) {
 
 // BaseDigestConfig creates a digest.Context from cmd.Context
 // that is needed to start the diff process
-func (c *Context) BaseDigestConfig(fs afero.Fs) (digest.Config, error) {
-	baseFile, err := fs.Open(c.BaseFilename)
-	if err != nil {
-		return digest.Config{}, err
-	}
-
-	c.baseFile = baseFile
-
+func (c *Context) BaseDigestConfig() (digest.Config, error) {
 	return digest.Config{
-		Reader:  baseFile,
-		Value:   c.ValueColumnPositions,
-		Key:     c.PrimaryKeyPositions,
-		Include: c.IncludeColumnPositions,
+		Reader:  c.baseFile,
+		Value:   c.valueColumnPositions,
+		Key:     c.primaryKeyPositions,
+		Include: c.includeColumnPositions,
 	}, nil
 }
 
 // DeltaDigestConfig creates a digest.Context from cmd.Context
 // that is needed to start the diff process
-func (c *Context) DeltaDigestConfig(fs afero.Fs) (digest.Config, error) {
-	deltaFile, err := fs.Open(c.DeltaFilename)
-	if err != nil {
-		return digest.Config{}, err
-	}
-
-	c.baseFile = deltaFile
-
+func (c *Context) DeltaDigestConfig() (digest.Config, error) {
 	return digest.Config{
-		Reader:  deltaFile,
-		Value:   c.ValueColumnPositions,
-		Key:     c.PrimaryKeyPositions,
-		Include: c.IncludeColumnPositions,
+		Reader:  c.deltaFile,
+		Value:   c.valueColumnPositions,
+		Key:     c.primaryKeyPositions,
+		Include: c.includeColumnPositions,
 	}, nil
 }