chore: 🧹 update imgcat and add support for kitty (#1017)

This could be done better by exposing more options from the protocol,
but it should be a good start!

sourced/imaging/imgcat.nu

@@ -1,91 +1,148 @@
 # https://iterm2.com/documentation-images.html
+# https://sw.kovidgoyal.net/kitty/graphics-protocol/
+
+def is-screen-term [] {
+  $env.TERM =~ ^screen
+}
 
 def print_osc [] {
-    if $env.TERM == screen* {
-        "\ePtmux;\e\e]"
-    } else {
-        "\e]"
-    }
+  if (is-screen-term) {
+    return "\ePtmux;\e\e]"
+  }
+  ansi escape_right
 }
 
 def print_st [] {
-    if $env.TERM == screen* {
-        "\a\e\\"
-    } else {
-        "\a"
-    }
+  if (is-screen-term) {
+    return "\a\e\\"
+  }
+  "\a"
 }
 
-def --env b64_encode [fn] {
-    open $fn | encode base64
+def b64_encode [fn] {
+  open -r $fn | encode base64
 }
 
-def --env b64_decode [fn] {
-    $fn | decode base64
-}
-
-def print_image [
-    filename # Filename to convey to client
-    inline # 0 or 1
-    base64contents # Base64-encoded contents
-    print_filename # If non-empty, print the filename before outputting the image
+# Print an image using the iTerm protocol
+def print_iterm_image [
+  filename: path
+  base64contents: string
+  --inline
+  --print_filename
 ] {
-    let a = (print_osc)
-    let b = "1337;File="
-    let c = (if ($filename | length) > 0 {
-        let b64_enc_data = (b64_encode $filename)
+  let b64_enc_data = (b64_encode $filename)
+  let b64_dec_data = ($base64contents | decode base64)
+  let query = (
+    [(print_osc)]
+    | append "1337;File="
+    | append (
+      if ($filename | str length) > 0 {
         $"name=($b64_enc_data);"
-    })
-    let b64_dec_data = (b64_decode $base64contents)
-    let d = $"size=($b64_dec_data | bytes length)"
-    let e = $";inline=($inline)"
-    let f = ":"
-    let g = $base64contents
-    let h = print_st
-    let i = "\n"
-    let j = (if ($print_filename | length) > 0 {
-        print -n $filename
-    })
+      }
+    )
+    | append $"size=($b64_dec_data | bytes length)"
+    | append (
+      if $inline {
+        $";inline=1"
+      }
+    )
+    | append ":"
+    | append $base64contents
+    | append (print_st)
+    | append "\n"
+  )
 
-    [ $a $b $c $d $e $f $g $h $i $j ] | str join
+  if $print_filename {
+    print -n $filename
+  }
+
+  $query | str join
+}
+
+# Print an image using the Kitty protocol
+def print_kitty_image [
+  filename: path
+  base64contents: string
+  --print_filename
+] {
+
+  let b64_dec_data = ($base64contents | decode base64)
+  let size = ($b64_dec_data | bytes length)
+
+  let result = (
+    ["\e"]
+    | append "_G"
+    | append $"a=T,f=100,t=d,s=($size);"
+    | append $base64contents
+    | append (ansi st)
+  )
+
+  if $print_filename {
+    print -n $filename
+  }
+
+  $result | str join
+}
+
+# Determine the appropriate protocol and print the image
+def print_image [
+  filename: path
+  base64contents: string
+  --inline # Only for iTerm; ignored for Kitty
+  --print_filename
+] {
+  if (detect_kitty_support) {
+    print_kitty_image $filename $base64contents --print_filename=$print_filename
+  } else {
+    print_iterm_image $filename $base64contents --inline=$inline --print_filename=$print_filename
+  }
 }
 
 def error [] {
-    print "Error: ($env.LAST_EXIT_CODE)"
+  print "Error: ($env.LAST_EXIT_CODE)"
 }
 
 def show_help [] {
-    print "Usage: imgcat [-p] filename ..."
-    print "   or: cat filename | imgcat"
+  print "Usage: imgcat [-p] filename ..."
+  print "   or: cat filename | imgcat"
+}
+
+# Detect Kitty support by querying the terminal
+# https://sw.kovidgoyal.net/kitty/graphics-protocol/#querying-support-and-available-transmission-mediums
+def detect_kitty_support [] {
+  let is_kitty_supported = $"(ansi esc)_Gi=1234,s=1,v=1,a=q,t=d,f=24;AAAA(ansi st)"
+  return (term query $is_kitty_supported --terminator (ansi st) | "OK" in ($in | decode))
+}
+
+export def detected [] {
+  print $"Kitty support: (detect_kitty_support)"
+  print $"Is Screen term: (is-screen-term)"
 }
 
 # imgcat.nu shows images in your terminal if your terminal supports it
-def imgcat [
-    --help(-h) # Help/Usage message
-    --print(-p) # Print filename
-    --url(-u) # Use a URL
-    filename # The filename to show
+# it uses either the Iterm or the Kitty protocol
+export def main [
+  --help (-h) # Help/Usage message
+  --print (-p) # Print filename
+  --url (-u) # Use a URL
+  --inline (-i) # Inline image (only for iTerm; ignored for Kitty)
+  filename # The filename to show
 ] {
-    if $help {
-        show_help
+  if $help {
+    show_help
+  }
+
+  let url_img = (
+    if $url {
+      let encoded_image = (b64_encode (http get $url))
+      print_image $url $encoded_image --inline=$inline --print_filename=$print
     }
+  )
 
-    let print_filename = (
-        if $print {
-            1
-        }
-    )
-
-    let url_img = (
-        if $url {
-            let encoded_image = (b64_encode (http get $url))
-            print_image $url 1 $encoded_image $print_filename
-        }
-    )
-
-    if ($filename | path exists) {
-        print_image $filename 1 (b64_encode $filename) $print_filename
-    } else {
-        print $"imgcat: ($filename): No such file or directory"
-    }
+  if ($filename | path exists) {
+    let filename = ($filename | path expand)
+    print_image $filename (b64_encode $filename) --inline=$inline --print_filename=$print
+  } else {
+    print $"imgcat: ($filename): No such file or directory"
+  }
 }