utils: terminal snippet

Author: krishpranav

src/utils/terminal_snippet.cr

@@ -19,26 +19,211 @@
 
 module MoonScript
   module TerminalSnippet
-    record Line, contents: String, index: Int64, offset: Int64 do
+    record Line, contents : String, index : Int64, offset : Int64 do
       def contains?(position)
         position >= offset && position <= (offset + size)
       end
 
-      def fully_contains?(form, to)
+      def fully_contains?(from, to)
         contains?(from, to) && (to - from) < contents.size
       end
 
       def contains?(from, to)
-        diff_from = from - offset
+        diff_from =
+          from - offset
 
-        diff_to = to - offset
+        diff_to =
+          to - offset
 
         diff_to > 0 && diff_from < contents.size
       end
 
       def size
         contents.size
       end
+
+      def highlight(from, to)
+        diff_from =
+          {from - offset, 0}.max
+
+        diff_to =
+          {[to - offset, contents.size].min, 0}.max
+
+        left =
+          self[0, diff_from]
+
+        center =
+          self[diff_from, diff_to]
+
+        right =
+          self[diff_to, contents.size]
+
+        highlighted =
+          left + center.colorize.on(:white).fore(:red).to_s + right
+
+        arrows =
+          (" " * left.size) + ("⌃" * center.size)
+
+        {highlighted, arrows}
+      end
+
+      def [](from, to)
+        contents[from, to - from]
+      rescue IndexError | ArgumentError
+        ""
+      end
+    end
+
+    extend self
+
+    def render(input : String, filename : String, from : Int64, to : Int64, padding = 4, width = 80)
+      path =
+        if (full = Path[filename]).absolute?
+          if full.expand.to_s.starts_with?(Dir.current.to_s)
+            full.relative_to?(Dir.current).try(&.to_s)
+          end
+        end || filename
+
+      # Transform each line into a record for further use.
+      lines =
+        input.lines.reduce({[] of Line, 0}) do |memo, raw|
+          items, index = memo
+
+          offset =
+            items.reduce(0) { |acc, item| acc + item.contents.size + 1 }
+
+          line =
+            Line.new(contents: raw, index: index, offset: offset)
+
+          {items + [line], index + 1}
+        end[0]
+
+      selected =
+        lines.select(&.contains?(from, to))
+
+      fully_highlighted =
+        selected.size == lines.size
+
+      # Get the first line which is the one we want to highlight minus the padding.
+      start_line =
+        {0, (lines.find(&.contains?(from)).try(&.index) || 0) - padding}.max
+
+      # Get the last line which is the one we want to highlight plus the padding.
+      end_line =
+        {(lines.find(&.contains?(to)).try(&.index) || 0) + padding + 1, lines.size}.min
+
+      # We need to calucluate the width of the gutter so we can pad later lon.
+      gutter_width = {
+        (start_line + 1).to_s.size,
+        (end_line + 1).to_s.size,
+      }.max
+
+      relevant_lines =
+        lines[start_line, end_line - start_line]
+
+      result =
+        relevant_lines.map do |line|
+          line_number =
+            (line.index + 1).to_s.rjust(gutter_width)
+
+          highlighted =
+            line.fully_contains?(from, to)
+
+          gutter =
+            if highlighted
+              "#{line_number}│".colorize(:light_yellow).mode(:bright)
+            else
+              "#{line_number}│".colorize.mode(:dim)
+            end
+
+          if fully_highlighted
+          elsif selected.size > 1 && selected.last == line
+            max_size =
+              selected.max_of(&.contents.size)
+
+            whitespace =
+              selected.min_of do |item|
+                count = 0
+                item.contents.each_char do |char|
+                  break unless char.ascii_whitespace?
+                  count += 1
+                end || 0
+                count
+              end
+
+            content_size =
+              max_size - whitespace
+
+            arrows =
+              "#{" " * whitespace}#{"⌃"*content_size}"
+
+            "#{gutter} #{line.contents}\n#{" " * gutter_width}│ #{arrows}"
+          elsif selected.size > 1 && selected.first == line
+            max_size =
+              selected.max_of(&.contents.size)
+
+            whitespace =
+              selected.min_of do |item|
+                count = 0
+                item.contents.each_char do |char|
+                  break unless char.ascii_whitespace?
+                  count += 1
+                end || 0
+                count
+              end
+
+            content_size =
+              max_size - whitespace
+
+            arrows =
+              "#{" " * whitespace}#{"⌄"*content_size}"
+
+            "#{" " * gutter_width}│ #{arrows}\n#{gutter} #{line.contents}"
+          elsif highlighted
+            a, b =
+              line.highlight(from, to)
+
+            "#{gutter} #{a}\n#{" " * gutter_width}│ #{b}"
+          elsif (from == input.size && line.offset + line.contents.size == from) ||
+                (line.offset + line.contents.size == (to - 1))
+            "#{gutter} #{line.contents}\n#{" " * gutter_width}│ #{" " * line.contents.size}⌃⌃⌃⌃"
+          end || "#{gutter} #{line.contents}"
+        end
+
+      line =
+        input[0..from].lines.size
+
+      column =
+        input[0..from].lines.last.size
+
+      title =
+        "#{path}:#{line}:#{column}"
+
+      gutter_divider =
+        " " * gutter_width
+
+      header_start =
+        "#{gutter_divider}┌ ".colorize.mode(:dim)
+
+      title_colorized =
+        title.colorize.mode(:bold)
+
+      header =
+        "#{header_start}#{title_colorized}"
+
+      header_divider_width =
+        [
+          header.uncolorize.size - (gutter_width + 1),
+          relevant_lines.max_of(&.size) + 1,
+        ].max
+
+      header_divider =
+        "#{gutter_divider}├" + ("─" * header_divider_width)
+
+      result =
+        result.join('\n')
+
+      "#{header}\n#{header_divider}\n#{result}"
     end
   end
 end