// RDEPUBPreferences.swift
// EPUB 阅读偏好设置
// 封装字号、行高、内容内边距、主题颜色、固定版式适配模式等展示参数，
// 并提供从偏好设置生成渲染请求和展示样式的便捷方法。

import UIKit

/// EPUB 阅读偏好设置，包含所有影响渲染效果的展示参数
public struct RDEPUBPreferences: Equatable {
    /// 字体大小（pt）
    public var fontSize: CGFloat
    /// 行高倍数（如 1.5 表示 1.5 倍行高）
    public var lineHeightMultiple: CGFloat
    /// 重排模式下的内容内边距
    public var reflowableContentInsets: UIEdgeInsets
    /// 固定版式下的内容内边距
    public var fixedContentInset: UIEdgeInsets
    /// 主题背景色（CSS 颜色值，如 "#FFFFFF"）
    public var themeBackgroundColor: String?
    /// 主题文字色（CSS 颜色值）
    public var themeTextColor: String?
    /// 固定版式背景色
    public var fixedBackgroundColor: String?
    /// 固定版式适配模式（page/width/height/contain/cover）
    public var fixedLayoutFit: RDEPUBFixedLayoutFit
    /// 固定版式双页展开模式（never/always/automatic）
    public var fixedLayoutSpreadMode: RDEPUBFixedLayoutSpreadMode
    /// 多栏排版栏数
    public var numberOfColumns: Int
    /// 多栏排版栏间距
    public var columnGap: CGFloat

    public init(
        fontSize: CGFloat,
        lineHeightMultiple: CGFloat,
        reflowableContentInsets: UIEdgeInsets,
        fixedContentInset: UIEdgeInsets,
        numberOfColumns: Int = 1,
        columnGap: CGFloat = 20,
        themeBackgroundColor: String? = nil,
        themeTextColor: String? = nil,
        fixedBackgroundColor: String? = nil,
        fixedLayoutFit: RDEPUBFixedLayoutFit = .page,
        fixedLayoutSpreadMode: RDEPUBFixedLayoutSpreadMode = .automatic
    ) {
        self.fontSize = fontSize
        self.lineHeightMultiple = lineHeightMultiple
        self.reflowableContentInsets = reflowableContentInsets
        self.fixedContentInset = fixedContentInset
        self.numberOfColumns = max(1, numberOfColumns)
        self.columnGap = max(0, columnGap)
        self.themeBackgroundColor = themeBackgroundColor
        self.themeTextColor = themeTextColor
        self.fixedBackgroundColor = fixedBackgroundColor
        self.fixedLayoutFit = fixedLayoutFit
        self.fixedLayoutSpreadMode = fixedLayoutSpreadMode
    }

    /// 从偏好设置生成重排模式的展示样式
    public func presentationStyle(viewportSize: CGSize) -> RDEPUBPresentationStyle {
        RDEPUBPresentationStyle(
            viewportSize: viewportSize,
            contentInsets: reflowableContentInsets,
            fontSize: fontSize,
            lineHeightMultiple: lineHeightMultiple,
            numberOfColumns: numberOfColumns,
            columnGap: columnGap,
            themeBackgroundColor: themeBackgroundColor,
            themeTextColor: themeTextColor
        )
    }

    /// 根据页面和偏好设置生成对应的渲染请求（自动区分固定版式和重排）
    public func renderRequest(
        for page: EPUBPage,
        publication: RDEPUBPublication,
        viewportSize: CGSize,
        targetLocation: RDEPUBLocation? = nil,
        targetHighlightRangeInfo: String? = nil,
        highlights: [RDEPUBHighlight] = [],
        searchPresentation: RDEPUBSearchPresentation? = nil
    ) -> RDEPUBRenderRequest? {
        if publication.layout == .fixed, let fixedSpread = page.fixedSpread {
            return .fixed(
                RDEPUBFixedRenderRequest(
                    spread: fixedSpread,
                    viewportSize: viewportSize,
                    contentInset: fixedContentInset,
                    backgroundColorCSS: fixedBackgroundColor,
                    fit: fixedLayoutFit,
                    searchPresentation: searchPresentation
                )
            )
        }

        guard publication.spine.indices.contains(page.spineIndex) else {
            return nil
        }

        return .reflowable(
            RDEPUBReflowableRenderRequest(
                spineIndex: page.spineIndex,
                href: publication.spine[page.spineIndex].href,
                pageIndex: page.pageIndexInChapter,
                totalPagesInChapter: page.totalPagesInChapter,
                presentation: presentationStyle(viewportSize: viewportSize),
                targetLocation: targetLocation,
                targetHighlightRangeInfo: targetHighlightRangeInfo,
                highlights: highlights,
                searchPresentation: searchPresentation
            )
        )
    }
}