import type { ResumeData, SectionType } from "@reactive-resume/schema/resume/data";
import type { Template } from "@reactive-resume/schema/templates";
import {
	BorderStyle,
	convertMillimetersToTwip,
	Document,
	ExternalHyperlink,
	HeadingLevel,
	Paragraph,
	ShadingType,
	Table,
	TableCell,
	TableRow,
	TextRun,
	WidthType,
} from "docx";
import { parseColorString } from "@reactive-resume/utils/color";
import { toSafeDocxLink } from "./link-utils";
import { renderBuiltInSection, renderCustomSection, renderSummary, setRenderConfig } from "./section-renderers";

// --- Color helpers ---

function rgbToHex(r: number, g: number, b: number): string {
	return [r, g, b].map((c) => c.toString(16).padStart(2, "0")).join("");
}

function getColorHex(rgba: string, fallback: string): string {
	const parsed = parseColorString(rgba);
	if (!parsed) return fallback;
	return rgbToHex(parsed.r, parsed.g, parsed.b);
}

// --- Unit conversion helpers ---

/** Convert pt font size to docx half-points (docx uses half-pt units). */
function ptToHalfPt(pt: number): number {
	return Math.round(pt * 2);
}

/** Convert pt spacing to twips (1pt = 20 twips). */
function ptToTwips(pt: number): number {
	return Math.round(pt * 20);
}

// --- Page size constants (in mm) ---

interface PageSize {
	width: number;
	height: number;
}

const DEFAULT_PAGE_SIZE: PageSize = { width: 210, height: 297 };

const PAGE_SIZES = {
	a4: DEFAULT_PAGE_SIZE,
	letter: { width: 215.9, height: 279.4 },
} satisfies Record<string, PageSize>;

type DocxPageFormat = keyof typeof PAGE_SIZES;

const resolveDocxPageFormat = (format: ResumeData["metadata"]["page"]["format"]): DocxPageFormat => {
	if (format === "letter") return "letter";

	return "a4";
};

// --- Invisible border preset for table cells ---

const NO_BORDERS = {
	top: { style: BorderStyle.NONE, size: 0 },
	bottom: { style: BorderStyle.NONE, size: 0 },
	left: { style: BorderStyle.NONE, size: 0 },
	right: { style: BorderStyle.NONE, size: 0 },
} as const;

// --- Template layout config ---

interface TemplateConfig {
	/** Which side the sidebar appears on */
	sidebarSide: "left" | "right" | "none";
	/** Sidebar background: "solid" = full primary color, "tint" = 20% opacity, "none" = no background */
	sidebarBackground: "solid" | "tint" | "none";
	/** Where the header is rendered */
	headerPosition: "full-width" | "main-only" | "sidebar-only";
}

const TEMPLATE_CONFIGS: Record<Template, TemplateConfig> = {
	azurill: { sidebarSide: "left", sidebarBackground: "none", headerPosition: "full-width" },
	bronzor: { sidebarSide: "right", sidebarBackground: "none", headerPosition: "full-width" },
	chikorita: { sidebarSide: "right", sidebarBackground: "solid", headerPosition: "main-only" },
	ditgar: { sidebarSide: "left", sidebarBackground: "tint", headerPosition: "sidebar-only" },
	ditto: { sidebarSide: "left", sidebarBackground: "none", headerPosition: "full-width" },
	gengar: { sidebarSide: "left", sidebarBackground: "tint", headerPosition: "sidebar-only" },
	glalie: { sidebarSide: "left", sidebarBackground: "tint", headerPosition: "sidebar-only" },
	kakuna: { sidebarSide: "right", sidebarBackground: "none", headerPosition: "full-width" },
	lapras: { sidebarSide: "right", sidebarBackground: "none", headerPosition: "full-width" },
	leafish: { sidebarSide: "right", sidebarBackground: "none", headerPosition: "full-width" },
	meowth: { sidebarSide: "left", sidebarBackground: "none", headerPosition: "full-width" },
	onyx: { sidebarSide: "right", sidebarBackground: "none", headerPosition: "full-width" },
	pikachu: { sidebarSide: "left", sidebarBackground: "none", headerPosition: "main-only" },
	rhyhorn: { sidebarSide: "right", sidebarBackground: "none", headerPosition: "full-width" },
	scizor: { sidebarSide: "left", sidebarBackground: "none", headerPosition: "full-width" },
};

const DEFAULT_TEMPLATE_CONFIG: TemplateConfig = {
	sidebarSide: "left",
	sidebarBackground: "none",
	headerPosition: "full-width",
};

/**
 * Blends a hex color toward white at the given opacity (0-1).
 * Used to approximate CSS `background-color: rgba(r,g,b, 0.2)` on a white background.
 */
function blendWithWhite(hex: string, opacity: number): string {
	const r = Number.parseInt(hex.slice(0, 2), 16);
	const g = Number.parseInt(hex.slice(2, 4), 16);
	const b = Number.parseInt(hex.slice(4, 6), 16);
	const blend = (c: number) => Math.round(c * opacity + 255 * (1 - opacity));
	return [blend(r), blend(g), blend(b)].map((c) => c.toString(16).padStart(2, "0")).join("");
}

// --- Section rendering dispatch ---

const BUILT_IN_SECTIONS = new Set<string>([
	"profiles",
	"experience",
	"education",
	"projects",
	"skills",
	"languages",
	"interests",
	"awards",
	"certifications",
	"publications",
	"volunteer",
	"references",
]);

function renderSection(sectionId: string, data: ResumeData, colorHex: string): Paragraph[] {
	if (sectionId === "summary") {
		return renderSummary(data.summary, colorHex);
	}

	if (BUILT_IN_SECTIONS.has(sectionId)) {
		const section = data.sections[sectionId as SectionType];
		if (section) {
			return renderBuiltInSection(sectionId as SectionType, section, colorHex);
		}
		return [];
	}

	const customSection = data.customSections.find((cs) => cs.id === sectionId);
	if (customSection) {
		return renderCustomSection(customSection, colorHex);
	}

	return [];
}

// --- Header ---

function buildHeader(data: ResumeData, colorHex: string, textColorHex: string): Paragraph[] {
	const paragraphs: Paragraph[] = [];
	const { basics } = data;
	const headingFont = data.metadata.typography.heading.fontFamily || "Calibri";
	const bodyFont = data.metadata.typography.body.fontFamily || "Calibri";
	// h2 = calc(var(--page-heading-font-size) * 1.25pt)
	const nameSize = ptToHalfPt(data.metadata.typography.heading.fontSize * 1.25);
	const bodySize = ptToHalfPt(data.metadata.typography.body.fontSize);

	if (basics.name) {
		paragraphs.push(
			new Paragraph({
				heading: HeadingLevel.TITLE,
				spacing: { after: 60 },
				children: [
					new TextRun({
						text: basics.name,
						bold: true,
						size: nameSize,
						font: headingFont,
						color: colorHex,
					}),
				],
			}),
		);
	}

	if (basics.headline) {
		paragraphs.push(
			new Paragraph({
				spacing: { after: 60 },
				children: [
					new TextRun({
						text: basics.headline,
						italics: true,
						size: bodySize,
						font: bodyFont,
						color: textColorHex,
					}),
				],
			}),
		);
	}

	const contactParts: (TextRun | ExternalHyperlink)[] = [];
	const addSeparator = () => {
		if (contactParts.length > 0) {
			contactParts.push(new TextRun({ text: "  |  ", color: "999999", size: bodySize, font: bodyFont }));
		}
	};

	if (basics.email) {
		const mailtoLink = toSafeDocxLink(`mailto:${basics.email}`);
		if (mailtoLink) {
			addSeparator();
			contactParts.push(
				new ExternalHyperlink({
					link: mailtoLink,
					children: [
						new TextRun({ text: basics.email, color: colorHex, underline: {}, size: bodySize, font: bodyFont }),
					],
				}),
			);
		}
	}

	if (basics.phone) {
		addSeparator();
		contactParts.push(new TextRun({ text: basics.phone, size: bodySize, font: bodyFont, color: textColorHex }));
	}

	if (basics.location) {
		addSeparator();
		contactParts.push(new TextRun({ text: basics.location, size: bodySize, font: bodyFont, color: textColorHex }));
	}

	if (basics.website.url) {
		const websiteLink = toSafeDocxLink(basics.website.url);
		if (websiteLink) {
			addSeparator();
			contactParts.push(
				new ExternalHyperlink({
					link: websiteLink,
					children: [
						new TextRun({
							text: basics.website.label || websiteLink,
							color: colorHex,
							underline: {},
							size: bodySize,
							font: bodyFont,
						}),
					],
				}),
			);
		}
	}

	for (const field of basics.customFields) {
		if (!field.text) continue;
		addSeparator();
		if (field.link) {
			const customLink = toSafeDocxLink(field.link);
			if (customLink) {
				contactParts.push(
					new ExternalHyperlink({
						link: customLink,
						children: [
							new TextRun({
								text: field.text,
								color: colorHex,
								underline: {},
								size: bodySize,
								font: bodyFont,
							}),
						],
					}),
				);
			} else {
				contactParts.push(new TextRun({ text: field.text, size: bodySize, font: bodyFont, color: textColorHex }));
			}
		} else {
			contactParts.push(new TextRun({ text: field.text, size: bodySize, font: bodyFont, color: textColorHex }));
		}
	}

	if (contactParts.length > 0) {
		paragraphs.push(
			new Paragraph({
				spacing: { after: 200 },
				children: contactParts,
			}),
		);
	}

	return paragraphs;
}

// --- Two-column table layout ---

function buildTwoColumnTable(
	mainParagraphs: Paragraph[],
	sidebarParagraphs: Paragraph[],
	sidebarWidthPct: number,
	gapXTwips: number,
	sidebarSide: "left" | "right" | "none",
	sidebarShadingHex?: string,
): Table {
	const mainWidthPct = 100 - sidebarWidthPct;

	// DOCX table cells require at least one child
	const mainChildren = mainParagraphs.length > 0 ? mainParagraphs : [new Paragraph({})];
	const sidebarChildren = sidebarParagraphs.length > 0 ? sidebarParagraphs : [new Paragraph({})];

	const sidebarShading = sidebarShadingHex
		? { fill: sidebarShadingHex, type: ShadingType.CLEAR, color: "auto" }
		: undefined;

	const margins: { right?: number; left?: number } = {};

	if (sidebarSide === "left") {
		margins.right = gapXTwips;
	} else if (sidebarSide === "right") {
		margins.left = gapXTwips;
	}

	const sidebarCell = new TableCell({
		width: { size: sidebarWidthPct, type: WidthType.PERCENTAGE },
		borders: NO_BORDERS,
		margins,
		children: sidebarChildren,
		...(sidebarShading ? { shading: sidebarShading } : {}),
	});

	const mainCell = new TableCell({
		width: { size: mainWidthPct, type: WidthType.PERCENTAGE },
		borders: NO_BORDERS,
		margins,
		children: mainChildren,
	});

	const cells = sidebarSide === "left" ? [sidebarCell, mainCell] : [mainCell, sidebarCell];

	return new Table({
		rows: [new TableRow({ children: cells })],
		width: { size: 100, type: WidthType.PERCENTAGE },
		borders: {
			top: { style: BorderStyle.NONE, size: 0 },
			bottom: { style: BorderStyle.NONE, size: 0 },
			left: { style: BorderStyle.NONE, size: 0 },
			right: { style: BorderStyle.NONE, size: 0 },
			insideHorizontal: { style: BorderStyle.NONE, size: 0 },
			insideVertical: { style: BorderStyle.NONE, size: 0 },
		},
	});
}

/**
 * Builds a complete docx Document from resume data.
 *
 * Mirrors the resume builder's visual layout:
 * - Header with name, headline, and contact info (centered, full-width)
 * - Two-column table layout (main + sidebar) matching `metadata.layout`
 * - Typography (font family, size, line height) from `metadata.typography`
 * - Page margins and fixed DOCX page format from `metadata.page`; free-form exports as A4
 * - Primary, text, and background colors from `metadata.design.colors`
 */
export function buildDocument(data: ResumeData): Document {
	const colorHex = getColorHex(data.metadata.design.colors.primary, "DC2626");
	const textColorHex = getColorHex(data.metadata.design.colors.text, "000000");
	const bgColorHex = getColorHex(data.metadata.design.colors.background, "FFFFFF");

	const bodyFont = data.metadata.typography.body.fontFamily || "Calibri";
	const bodySize = ptToHalfPt(data.metadata.typography.body.fontSize);
	const lineSpacing = Math.round(data.metadata.typography.body.lineHeight * 240);

	const { page } = data.metadata;
	const pageSize = PAGE_SIZES[resolveDocxPageFormat(page.format)];
	// Margins and gaps are defined in points (pt), not mm
	const marginXTwips = ptToTwips(page.marginX);
	const marginYTwips = ptToTwips(page.marginY);
	const gapXTwips = ptToTwips(page.gapX);

	const sidebarWidth = data.metadata.layout.sidebarWidth;

	// Template-aware layout config
	const templateConfig = TEMPLATE_CONFIGS[data.metadata.template] ?? DEFAULT_TEMPLATE_CONFIG;

	// Compute sidebar background shading hex
	let sidebarShadingHex: string | undefined;
	if (templateConfig.sidebarBackground === "solid") {
		sidebarShadingHex = colorHex;
	} else if (templateConfig.sidebarBackground === "tint") {
		sidebarShadingHex = blendWithWhite(colorHex, 0.2);
	}

	// Determine sidebar text colors — inverted when sidebar has a solid background
	const sidebarTextColorHex = templateConfig.sidebarBackground === "solid" ? bgColorHex : textColorHex;
	const sidebarHeadingColorHex = templateConfig.sidebarBackground === "solid" ? bgColorHex : colorHex;

	// Configure heading typography for section renderers
	const headingFont = data.metadata.typography.heading.fontFamily || "Calibri";
	const headingSize = ptToHalfPt(data.metadata.typography.heading.fontSize);

	const documentChildren: (Paragraph | Table)[] = [];

	// Header placement depends on template
	if (templateConfig.headerPosition === "full-width") {
		// Configure colors for main content
		setRenderConfig({
			headingFont,
			headingSizeHalfPt: headingSize,
			bodyFont,
			bodySizeHalfPt: bodySize,
			textColorHex,
			primaryColorHex: colorHex,
		});
		documentChildren.push(...buildHeader(data, colorHex, textColorHex));
	}

	// Process each page in the layout
	for (const layoutPage of data.metadata.layout.pages) {
		const isFullWidth = layoutPage.fullWidth || layoutPage.sidebar.length === 0;

		if (isFullWidth) {
			setRenderConfig({
				headingFont,
				headingSizeHalfPt: headingSize,
				bodyFont,
				bodySizeHalfPt: bodySize,
				textColorHex,
				primaryColorHex: colorHex,
			});
			for (const sectionId of [...layoutPage.main, ...layoutPage.sidebar]) {
				documentChildren.push(...renderSection(sectionId, data, colorHex));
			}
		} else {
			// Render main sections with normal colors
			setRenderConfig({
				headingFont,
				headingSizeHalfPt: headingSize,
				bodyFont,
				bodySizeHalfPt: bodySize,
				textColorHex,
				primaryColorHex: colorHex,
			});

			const mainParagraphs: Paragraph[] = [];
			if (templateConfig.headerPosition === "main-only") {
				mainParagraphs.push(...buildHeader(data, colorHex, textColorHex));
			}
			for (const sectionId of layoutPage.main) {
				mainParagraphs.push(...renderSection(sectionId, data, colorHex));
			}

			// Render sidebar sections with potentially inverted colors
			setRenderConfig({
				headingFont,
				headingSizeHalfPt: headingSize,
				bodyFont,
				bodySizeHalfPt: bodySize,
				textColorHex: sidebarTextColorHex,
				primaryColorHex: sidebarHeadingColorHex,
			});

			const sidebarParagraphs: Paragraph[] = [];
			if (templateConfig.headerPosition === "sidebar-only") {
				sidebarParagraphs.push(...buildHeader(data, sidebarHeadingColorHex, sidebarTextColorHex));
			}
			for (const sectionId of layoutPage.sidebar) {
				sidebarParagraphs.push(...renderSection(sectionId, data, sidebarHeadingColorHex));
			}

			if (mainParagraphs.length > 0 || sidebarParagraphs.length > 0) {
				documentChildren.push(
					buildTwoColumnTable(
						mainParagraphs,
						sidebarParagraphs,
						sidebarWidth,
						gapXTwips,
						templateConfig.sidebarSide,
						sidebarShadingHex,
					),
				);
			}
		}
	}

	return new Document({
		styles: {
			default: {
				document: {
					run: {
						font: bodyFont,
						size: bodySize,
						color: textColorHex,
					},
					paragraph: {
						spacing: { line: lineSpacing },
					},
				},
			},
		},
		...(bgColorHex !== "FFFFFF" ? { background: { color: bgColorHex } } : {}),
		sections: [
			{
				properties: {
					page: {
						size: {
							width: convertMillimetersToTwip(pageSize.width),
							height: convertMillimetersToTwip(pageSize.height),
						},
						margin: {
							top: marginYTwips,
							bottom: marginYTwips,
							left: marginXTwips,
							right: marginXTwips,
						},
					},
				},
				children: documentChildren,
			},
		],
	});
}