// Copyright 2025-2026 肖其顿 (XIAO QI DUN)
//
// 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.

package pdf

import (
	"github.com/xiaoqidun/pdfgo"
)

// PageMatrix 将裁剪框、用户单位及页面旋转转换为OFD毫米坐标
// 入参: page PDF页面
// 返回: pdfgo.Matrix 坐标变换, float64 页面宽度, float64 页面高度
func PageMatrix(page *pdfgo.Page) (pdfgo.Matrix, float64, float64) {
	b := page.CropBox
	scale := 25.4 / 72 * page.UserUnit
	width, height := (b.XMax-b.XMin)*scale, (b.YMax-b.YMin)*scale
	m := pdfgo.Matrix{scale, 0, 0, -scale, -b.XMin * scale, b.YMax * scale}
	switch page.Rotation {
	case 90:
		m = pdfgo.Matrix{0, 1, -1, 0, height, 0}.Mul(m)
		width, height = height, width
	case 180:
		m = pdfgo.Matrix{-1, 0, 0, -1, width, height}.Mul(m)
	case 270:
		m = pdfgo.Matrix{0, -1, 1, 0, 0, width}.Mul(m)
		width, height = height, width
	}
	return m, width, height
}