Add support for formatting CSVs

README.md

@@ -6,7 +6,7 @@
 
 ### Features include:
 
-- **Response formatting**: automatically formats and colors output (json, html, msgpack, protobuf, xml, etc.)
+- **Response formatting**: automatically formats and colors output (json, html, csv, msgpack, protobuf, xml, etc.)
 - **Image rendering**: render images directly in your terminal
 - **Compression**: automatic gzip and zstd response body decompression
 - **Authentication**: support for Basic Auth, Bearer Token, and AWS Signature V4

docs/USAGE.md

@@ -336,11 +336,14 @@ Supported formats for automatic formatting and syntax highlighting:
 - JSON (`application/json`)
 - HTML (`text/html`)
 - XML (`application/xml`, `text/xml`)
+- CSV (`text/csv`)
 - MessagePack (`application/msgpack`)
 - NDJSON/JSONLines (`application/x-ndjson`)
 - Protobuf (`application/x-protobuf`, `application/protobuf`)
 - Server-Sent Events (`text/event-stream`)
 
+CSV output is automatically column-aligned. When output is too wide for the terminal, it switches to a vertical "record view" format where each row is displayed with field names as labels.
+
 ```sh
 fetch --format off example.com
 fetch --format on example.com

go.mod

@@ -4,6 +4,7 @@ go 1.25.6
 
 require (
 	github.com/klauspost/compress v1.18.3
+	github.com/mattn/go-runewidth v0.0.19
 	github.com/quic-go/quic-go v0.59.0
 	github.com/tinylib/msgp v1.6.3
 	golang.org/x/image v0.35.0
@@ -13,6 +14,7 @@ require (
 )
 
 require (
+	github.com/clipperhouse/uax29/v2 v2.2.0 // indirect
 	github.com/philhofer/fwd v1.2.0 // indirect
 	github.com/quic-go/qpack v0.6.0 // indirect
 	golang.org/x/crypto v0.47.0 // indirect

go.sum

@@ -1,7 +1,11 @@
+github.com/clipperhouse/uax29/v2 v2.2.0 h1:ChwIKnQN3kcZteTXMgb1wztSgaU+ZemkgWdohwgs8tY=
+github.com/clipperhouse/uax29/v2 v2.2.0/go.mod h1:EFJ2TJMRUaplDxHKj1qAEhCtQPW2tJSwu5BF98AuoVM=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/klauspost/compress v1.18.3 h1:9PJRvfbmTabkOX8moIpXPbMMbYN60bWImDDU7L+/6zw=
 github.com/klauspost/compress v1.18.3/go.mod h1:R0h/fSBs8DE4ENlcrlib3PsXS61voFxhIs2DeRhCvJ4=
+github.com/mattn/go-runewidth v0.0.19 h1:v++JhqYnZuu5jSKrk9RbgF5v4CGUjqRfBm05byFGLdw=
+github.com/mattn/go-runewidth v0.0.19/go.mod h1:XBkDxAl56ILZc9knddidhrOlY5R/pDhgLpndooCuJAs=
 github.com/philhofer/fwd v1.2.0 h1:e6DnBTl7vGY+Gz322/ASL4Gyp1FspeMvx1RNDoToZuM=
 github.com/philhofer/fwd v1.2.0/go.mod h1:RqIHx9QI14HlwKwm98g9Re5prTQ6LdeRQn+gXJFxsJM=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=

internal/core/term_size_unix.go

@@ -0,0 +1,33 @@
+//go:build unix
+
+package core
+
+import (
+	"os"
+
+	"golang.org/x/sys/unix"
+)
+
+// GetTerminalSize returns the terminal size, or an error if unavailable.
+func GetTerminalSize() (TerminalSize, error) {
+	var ts TerminalSize
+	ws, err := unix.IoctlGetWinsize(int(os.Stdout.Fd()), unix.TIOCGWINSZ)
+	if err != nil {
+		return ts, err
+	}
+
+	ts.Cols = int(ws.Col)
+	ts.Rows = int(ws.Row)
+	ts.WidthPx = int(ws.Xpixel)
+	ts.HeightPx = int(ws.Ypixel)
+	return ts, nil
+}
+
+// GetTerminalCols returns the number of columns in the terminal, or 0 if unavailable.
+func GetTerminalCols() int {
+	ts, err := GetTerminalSize()
+	if err != nil {
+		return 0
+	}
+	return ts.Cols
+}

internal/core/term_size_windows.go

@@ -0,0 +1,37 @@
+//go:build windows
+
+package core
+
+import (
+	"os"
+
+	"golang.org/x/sys/windows"
+)
+
+// GetTerminalSize returns the terminal size, or an error if unavailable.
+func GetTerminalSize() (TerminalSize, error) {
+	var ts TerminalSize
+
+	var info windows.ConsoleScreenBufferInfo
+	handle := windows.Handle(int(os.Stdout.Fd()))
+	err := windows.GetConsoleScreenBufferInfo(handle, &info)
+	if err != nil {
+		return ts, err
+	}
+
+	ts.Cols = int(info.Window.Right - info.Window.Left + 1)
+	ts.Rows = int(info.Window.Bottom - info.Window.Top + 1)
+	// Windows console doesn't provide pixel dimensions
+	ts.WidthPx = 0
+	ts.HeightPx = 0
+	return ts, nil
+}
+
+// GetTerminalCols returns the number of columns in the terminal, or 0 if unavailable.
+func GetTerminalCols() int {
+	ts, err := GetTerminalSize()
+	if err != nil {
+		return 0
+	}
+	return ts.Cols
+}

internal/core/vars.go

@@ -6,6 +6,14 @@ import (
 	"runtime/debug"
 )
 
+// TerminalSize represents the dimensions of the terminal.
+type TerminalSize struct {
+	Cols     int // Number of columns (characters)
+	Rows     int // Number of rows (characters)
+	WidthPx  int // Width in pixels (0 if unavailable)
+	HeightPx int // Height in pixels (0 if unavailable)
+}
+
 var (
 	IsStderrTerm bool
 	IsStdoutTerm bool

internal/fetch/fetch.go

@@ -28,6 +28,7 @@ type ContentType int
 
 const (
 	TypeUnknown ContentType = iota
+	TypeCSV
 	TypeHTML
 	TypeImage
 	TypeJSON
@@ -285,6 +286,10 @@ func formatResponse(ctx context.Context, r *Request, resp *http.Response) (io.Re
 	}
 
 	switch contentType {
+	case TypeCSV:
+		if format.FormatCSV(buf, p) == nil {
+			buf = p.Bytes()
+		}
 	case TypeHTML:
 		if format.FormatHTML(buf, p) == nil {
 			buf = p.Bytes()
@@ -328,6 +333,8 @@ func getContentType(headers http.Header) ContentType {
 			return TypeImage
 		case "application":
 			switch subtype {
+			case "csv":
+				return TypeCSV
 			case "json":
 				return TypeJSON
 			case "msgpack", "x-msgpack", "vnd.msgpack":
@@ -350,6 +357,8 @@ func getContentType(headers http.Header) ContentType {
 			}
 		case "text":
 			switch subtype {
+			case "csv":
+				return TypeCSV
 			case "html":
 				return TypeHTML
 			case "event-stream":

internal/format/csv.go

@@ -0,0 +1,209 @@
+package format
+
+import (
+	"bytes"
+	"encoding/csv"
+	"fmt"
+	"strings"
+
+	"github.com/ryanfowler/fetch/internal/core"
+
+	"github.com/mattn/go-runewidth"
+)
+
+// FormatCSV formats the provided CSV data to the Printer.
+func FormatCSV(buf []byte, p *core.Printer) error {
+	err := formatCSV(buf, p)
+	if err != nil {
+		p.Reset()
+	}
+	return err
+}
+
+func formatCSV(buf []byte, p *core.Printer) error {
+	if len(buf) == 0 {
+		return nil
+	}
+
+	delimiter := detectDelimiter(buf)
+
+	reader := csv.NewReader(bytes.NewReader(buf))
+	reader.Comma = delimiter
+	reader.FieldsPerRecord = -1 // Allow ragged rows
+	reader.LazyQuotes = true    // Lenient parsing
+
+	records, err := reader.ReadAll()
+	if err != nil {
+		return err
+	}
+	if len(records) == 0 {
+		return nil
+	}
+
+	// Calculate column widths
+	colWidths := calculateColumnWidths(records)
+	totalWidth := calculateTotalWidth(colWidths)
+	termCols := core.GetTerminalCols()
+
+	// Use vertical mode if terminal width is known and content exceeds it
+	if termCols > 0 && totalWidth > termCols && len(records) > 1 {
+		return writeVertical(p, records)
+	}
+
+	// Output formatted rows (horizontal mode)
+	for i, row := range records {
+		if i > 0 {
+			p.WriteString("\n")
+		}
+		writeRow(p, row, colWidths, i == 0)
+	}
+	p.WriteString("\n")
+
+	return nil
+}
+
+// detectDelimiter auto-detects the delimiter from the first line.
+// Checks comma, tab, semicolon, and pipe. Defaults to comma.
+func detectDelimiter(buf []byte) rune {
+	// Find the first line
+	firstLine, _, _ := bytes.Cut(buf, []byte{'\n'})
+
+	delimiters := []rune{',', '\t', ';', '|'}
+	counts := make(map[rune]int)
+
+	for _, d := range delimiters {
+		counts[d] = strings.Count(string(firstLine), string(d))
+	}
+
+	// Pick the delimiter with the highest count
+	maxCount := 0
+	bestDelimiter := ','
+	for _, d := range delimiters {
+		if counts[d] > maxCount {
+			maxCount = counts[d]
+			bestDelimiter = d
+		}
+	}
+
+	return bestDelimiter
+}
+
+// calculateColumnWidths finds the max display width per column across all rows.
+func calculateColumnWidths(records [][]string) []int {
+	if len(records) == 0 {
+		return nil
+	}
+
+	// Find max number of columns
+	maxCols := 0
+	for _, row := range records {
+		if len(row) > maxCols {
+			maxCols = len(row)
+		}
+	}
+
+	widths := make([]int, maxCols)
+	for _, row := range records {
+		for j, cell := range row {
+			w := runewidth.StringWidth(cell)
+			if w > widths[j] {
+				widths[j] = w
+			}
+		}
+	}
+
+	return widths
+}
+
+// calculateTotalWidth returns the total display width of horizontal output.
+func calculateTotalWidth(colWidths []int) int {
+	total := 0
+	for _, w := range colWidths {
+		total += w
+	}
+	if len(colWidths) > 1 {
+		total += (len(colWidths) - 1) * 2 // separator width ("  ")
+	}
+	return total
+}
+
+// writeRow writes a single row with proper alignment and coloring.
+func writeRow(p *core.Printer, row []string, colWidths []int, isHeader bool) {
+	for j, cell := range row {
+		if j > 0 {
+			p.WriteString("  ") // Column separator
+		}
+
+		// Apply color
+		if isHeader {
+			p.Set(core.Blue)
+			p.Set(core.Bold)
+		} else {
+			p.Set(core.Green)
+		}
+
+		p.WriteString(cell)
+		p.Reset()
+
+		// Add padding for alignment (except for the last column)
+		if j < len(colWidths)-1 {
+			cellWidth := runewidth.StringWidth(cell)
+			padding := colWidths[j] - cellWidth
+			for range padding {
+				p.WriteString(" ")
+			}
+		}
+	}
+}
+
+// writeVertical renders each data row as a vertical record with field labels.
+func writeVertical(p *core.Printer, records [][]string) error {
+	headers := records[0]
+
+	// Calculate max header display width for right-alignment
+	maxHeaderWidth := 0
+	for _, h := range headers {
+		if w := runewidth.StringWidth(h); w > maxHeaderWidth {
+			maxHeaderWidth = w
+		}
+	}
+
+	for i, row := range records[1:] { // Skip header row
+		if i > 0 {
+			p.WriteString("\n")
+		}
+
+		// Row separator
+		p.Set(core.Dim)
+		fmt.Fprintf(p, "--- Row %d ---\n", i+1)
+		p.Reset()
+
+		for j, cell := range row {
+			header := ""
+			if j < len(headers) {
+				header = headers[j]
+			}
+
+			// Right-align header using display width
+			padding := maxHeaderWidth - runewidth.StringWidth(header)
+			for range padding {
+				p.WriteString(" ")
+			}
+
+			// Header in blue+bold
+			p.Set(core.Blue)
+			p.Set(core.Bold)
+			p.WriteString(header)
+			p.Reset()
+			p.WriteString(": ")
+
+			// Value in green
+			p.Set(core.Green)
+			p.WriteString(cell)
+			p.Reset()
+			p.WriteString("\n")
+		}
+	}
+
+	return nil
+}