feat: decoding improvements (#2068)

* refactor: moved/simplified snippets into its own file with tests

* refactor: move snippet to taskfile package

* feat: support snippets with line/col = 0

* feat: functional options for snippets

* feat: added option to hide snippet indicators

* feat: store raw lines for length calculations

* feat: add debug function for TaskfileDecodeError

* fix: decode errors from commands

* fix: schema for defer cmd calls

* fix: linting issues

* refactor: split var and vars into different files like other structures

taskfile/snippet.go

@@ -0,0 +1,148 @@
+package taskfile
+
+import (
+	"bytes"
+	"embed"
+	"fmt"
+	"strings"
+
+	"github.com/alecthomas/chroma/v2"
+	"github.com/alecthomas/chroma/v2/quick"
+	"github.com/alecthomas/chroma/v2/styles"
+	"github.com/fatih/color"
+)
+
+//go:embed themes/*.xml
+var embedded embed.FS
+
+const (
+	lineIndicator   = ">"
+	columnIndicator = "^"
+)
+
+func init() {
+	r, err := embedded.Open("themes/task.xml")
+	if err != nil {
+		panic(err)
+	}
+	style, err := chroma.NewXMLStyle(r)
+	if err != nil {
+		panic(err)
+	}
+	styles.Register(style)
+}
+
+type (
+	SnippetOption func(*Snippet)
+	Snippet       struct {
+		linesRaw         []string
+		linesHighlighted []string
+		start            int
+		end              int
+		line             int
+		column           int
+		padding          int
+		noIndicators     bool
+	}
+)
+
+// NewSnippet creates a new snippet from a byte slice and a line and column
+// number. The line and column numbers should be 1-indexed. For example, the
+// first character in the file would be 1:1 (line 1, column 1). The padding
+// determines the number of lines to include before and after the chosen line.
+func NewSnippet(b []byte, opts ...SnippetOption) *Snippet {
+	snippet := &Snippet{}
+	for _, opt := range opts {
+		opt(snippet)
+	}
+
+	// Syntax highlight the input and split it into lines
+	buf := &bytes.Buffer{}
+	if err := quick.Highlight(buf, string(b), "yaml", "terminal", "task"); err != nil {
+		buf.WriteString(string(b))
+	}
+	linesRaw := strings.Split(string(b), "\n")
+	linesHighlighted := strings.Split(buf.String(), "\n")
+
+	// Work out the start and end lines of the snippet
+	snippet.start = max(snippet.line-snippet.padding, 1)
+	snippet.end = min(snippet.line+snippet.padding, len(linesRaw)-1)
+	snippet.linesRaw = linesRaw[snippet.start-1 : snippet.end]
+	snippet.linesHighlighted = linesHighlighted[snippet.start-1 : snippet.end]
+
+	return snippet
+}
+
+func SnippetWithLine(line int) SnippetOption {
+	return func(snippet *Snippet) {
+		snippet.line = line
+	}
+}
+
+func SnippetWithColumn(column int) SnippetOption {
+	return func(snippet *Snippet) {
+		snippet.column = column
+	}
+}
+
+func SnippetWithPadding(padding int) SnippetOption {
+	return func(snippet *Snippet) {
+		snippet.padding = padding
+	}
+}
+
+func SnippetWithNoIndicators() SnippetOption {
+	return func(snippet *Snippet) {
+		snippet.noIndicators = true
+	}
+}
+
+func (snippet *Snippet) String() string {
+	buf := &bytes.Buffer{}
+
+	maxLineNumberDigits := digits(snippet.end)
+	lineNumberFormat := fmt.Sprintf("%%%dd", maxLineNumberDigits)
+	lineNumberSpacer := strings.Repeat(" ", maxLineNumberDigits)
+	lineIndicatorSpacer := strings.Repeat(" ", len(lineIndicator))
+	columnSpacer := strings.Repeat(" ", max(snippet.column-1, 0))
+
+	// Loop over each line in the snippet
+	for i, lineHighlighted := range snippet.linesHighlighted {
+		if i > 0 {
+			fmt.Fprintln(buf)
+		}
+
+		currentLine := snippet.start + i
+		lineNumber := fmt.Sprintf(lineNumberFormat, currentLine)
+
+		// If this is a padding line or indicators are disabled, print it as normal
+		if currentLine != snippet.line || snippet.noIndicators {
+			fmt.Fprintf(buf, "%s %s | %s", lineIndicatorSpacer, lineNumber, lineHighlighted)
+			continue
+		}
+
+		// Otherwise, print the line with indicators
+		fmt.Fprintf(buf, "%s %s | %s", color.RedString(lineIndicator), lineNumber, lineHighlighted)
+
+		// Only print the column indicator if the column is in bounds
+		if snippet.column > 0 && snippet.column <= len(snippet.linesRaw[i]) {
+			fmt.Fprintf(buf, "\n%s %s | %s%s", lineIndicatorSpacer, lineNumberSpacer, columnSpacer, color.RedString(columnIndicator))
+		}
+	}
+
+	// If there are lines, but no line is selected, print the column indicator under all the lines
+	if len(snippet.linesHighlighted) > 0 && snippet.line == 0 && snippet.column > 0 {
+		fmt.Fprintf(buf, "\n%s %s | %s%s", lineIndicatorSpacer, lineNumberSpacer, columnSpacer, color.RedString(columnIndicator))
+	}
+
+	return buf.String()
+}
+
+func digits(number int) int {
+	count := 0
+	for number != 0 {
+		number /= 10
+		count += 1
+	}
+	return count
+}