// Copyright 2026 Ling71671
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

///|
/// Helper to convert a Color to standard CSS rgb(...) string.
fn color_to_rgb(c : @color.Color) -> String {
  "rgb(" + c.r.to_string() + "," + c.g.to_string() + "," + c.b.to_string() + ")"
}

///|
/// Helper to compute opacity string from alpha byte.
fn color_to_opacity(c : @color.Color) -> String {
  if c.a == 255 {
    "1"
  } else if c.a == 0 {
    "0"
  } else {
    // 2 decimal places approximation
    let pct = (c.a.to_double() / 255.0 * 100.0).to_int()
    let int_part = pct / 100
    let dec_part = pct % 100
    let dec_str = if dec_part < 10 {
      "0" + dec_part.to_string()
    } else {
      dec_part.to_string()
    }
    int_part.to_string() + "." + dec_str
  }
}

///|
/// Escape standard XML entities for safe SVG output.
fn escape_xml(s : String) -> String {
  let buf = StringBuilder()
  for c in s {
    match c {
      '&' => buf.write_string("&")
      '<' => buf.write_string("<")
      '>' => buf.write_string(">")
      '"' => buf.write_string(""")
      '\'' => buf.write_string("'")
      _ => buf.write_char(c)
    }
  }
  buf.to_string()
}

///|
/// SvgExporter converts a DrawList into compliant standalone SVG XML markup.
pub struct SvgExporter {
  width : Double
  height : Double
  background : @color.Color?
} derive(Eq, Debug)

///|
pub fn SvgExporter::new(
  width : Double,
  height : Double,
  background? : @color.Color,
) -> SvgExporter {
  { width, height, background, }
}

///|
/// Renders the given DrawList as a standard standalone SVG string.
pub fn SvgExporter::render_to_string(
  self : SvgExporter,
  draw_list : DrawList,
) -> String {
  let buf = StringBuilder()

  buf.write_string("\n")
  buf.to_string()
}

///|
/// Convenience extension method on DrawList to render directly to SVG.
pub fn DrawList::to_svg(
  self : DrawList,
  width : Double,
  height : Double,
  background? : @color.Color,
) -> String {
  let exporter = SvgExporter::new(width, height, background?)
  exporter.render_to_string(self)
}