//! Transforms Demo - Rotation, Scaling, Skew, and Translation
//!
//! Demonstrates the transformation capabilities of zpdf including:
//! - Rotation around a point
//! - Scaling from a point
//! - Skewing (shearing)
//! - Translation
//! - Combined transformations

const std = @import("std");
const pdf = @import("zpdf");

pub fn main() !void {
    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
    defer _ = gpa.deinit();
    const allocator = gpa.allocator();

    std.debug.print("zpdf - Transforms Demo\n", .{});

    var doc = pdf.Pdf.init(allocator, .{});
    defer doc.deinit();

    doc.setTitle("Transforms Demo");
    doc.setAuthor("zpdf");

    // =========================================================================
    // Page 1: Rotation
    // =========================================================================
    {
        const page = try doc.addPage(.{});

        // Title
        try page.setFont(.helvetica_bold, 24);
        page.setFillColor(pdf.Color.rgb(41, 98, 255));
        try page.drawText(50, 780, "Rotation Transforms");

        try page.setFont(.helvetica, 11);
        page.setFillColor(pdf.Color.black);
        try page.drawText(50, 755, "Rotate graphics around a specified point");

        // Original rectangle (for reference)
        try page.setFont(.helvetica, 10);
        page.setFillColor(pdf.Color.dark_gray);
        try page.drawText(100, 680, "Original:");

        page.setFillColor(pdf.Color.rgb(200, 200, 200));
        page.setStrokeColor(pdf.Color.black);
        try page.setLineWidth(1);
        try page.drawFilledRect(100, 600, 80, 60);

        // Draw rotation center marker
        page.setFillColor(pdf.Color.red);
        try page.fillCircle(140, 630, 3);

        // Rotated rectangles
        const angles = [_]f32{ 15, 30, 45, 60 };
        const colors = [_]pdf.Color{
            pdf.Color.rgb(255, 100, 100),
            pdf.Color.rgb(100, 255, 100),
            pdf.Color.rgb(100, 100, 255),
            pdf.Color.rgb(255, 200, 100),
        };

        var x: f32 = 250;
        for (angles, colors) |angle, color| {
            try page.setFont(.helvetica, 9);
            page.setFillColor(pdf.Color.dark_gray);

            var angle_buf: [32]u8 = undefined;
            const angle_str = std.fmt.bufPrint(&angle_buf, "{d} degrees", .{@as(i32, @intFromFloat(angle))}) catch "angle";
            try page.drawText(x, 680, angle_str);

            // Save state before transformation
            try page.saveState();

            // Rotate around center of rectangle
            const cx = x + 40;
            const cy: f32 = 630;
            try page.rotate(angle, cx, cy);

            // Draw rectangle
            page.setFillColor(color);
            page.setStrokeColor(pdf.Color.black);
            try page.drawFilledRect(x, 600, 80, 60);

            // Restore state
            try page.restoreState();

            // Draw center point
            page.setFillColor(pdf.Color.red);
            try page.fillCircle(cx, cy, 3);

            x += 100;
        }

        // Rotated text example
        try page.setFont(.helvetica_bold, 14);
        page.setFillColor(pdf.Color.black);
        try page.drawText(50, 520, "Rotated Text:");

        const text_angles = [_]f32{ 0, 15, 30, 45, 90 };
        x = 100;
        for (text_angles) |angle| {
            try page.saveState();
            try page.rotate(angle, x, 450);

            try page.setFont(.helvetica, 12);
            page.setFillColor(pdf.Color.rgb(0, 100, 150));
            try page.drawText(x, 450, "Hello!");

            try page.restoreState();

            x += 80;
        }

        // Multiple rotations around same point (like clock hands)
        try page.setFont(.helvetica_bold, 14);
        page.setFillColor(pdf.Color.black);
        try page.drawText(50, 350, "Clock-like Rotation:");

        const clock_cx: f32 = 200;
        const clock_cy: f32 = 250;

        // Draw clock circle
        page.setStrokeColor(pdf.Color.dark_gray);
        try page.setLineWidth(2);
        try page.drawCircle(clock_cx, clock_cy, 80);

        // Draw hour marks
        try page.setLineWidth(1);
        for (0..12) |i| {
            const fi: f32 = @floatFromInt(i);
            try page.saveState();
            try page.rotate(fi * 30, clock_cx, clock_cy);

            page.setStrokeColor(pdf.Color.dark_gray);
            try page.drawLine(clock_cx, clock_cy + 70, clock_cx, clock_cy + 80);

            try page.restoreState();
        }

        // Draw clock hands
        try page.setLineWidth(3);
        page.setStrokeColor(pdf.Color.rgb(50, 50, 150));
        try page.saveState();
        try page.rotate(60, clock_cx, clock_cy); // Hour hand at ~2 o'clock
        try page.drawLine(clock_cx, clock_cy, clock_cx, clock_cy + 45);
        try page.restoreState();

        try page.setLineWidth(2);
        page.setStrokeColor(pdf.Color.rgb(150, 50, 50));
        try page.saveState();
        try page.rotate(210, clock_cx, clock_cy); // Minute hand at ~7 o'clock
        try page.drawLine(clock_cx, clock_cy, clock_cx, clock_cy + 65);
        try page.restoreState();

        // Footer
        try page.setFont(.helvetica, 9);
        page.setFillColor(pdf.Color.medium_gray);
        try page.drawText(250, 50, "Page 1 of 2 - zpdf Transforms Demo");
    }

    // =========================================================================
    // Page 2: Scale, Skew, and Combined Transforms
    // =========================================================================
    {
        const page = try doc.addPage(.{});

        // Title
        try page.setFont(.helvetica_bold, 24);
        page.setFillColor(pdf.Color.rgb(41, 98, 255));
        try page.drawText(50, 780, "Scale, Skew & Combined");

        // Scaling section
        try page.setFont(.helvetica_bold, 14);
        page.setFillColor(pdf.Color.black);
        try page.drawText(50, 720, "Scaling:");

        try page.setFont(.helvetica, 10);
        page.setFillColor(pdf.Color.dark_gray);
        try page.drawText(50, 700, "Scale graphics from a reference point");

        // Original
        page.setFillColor(pdf.Color.light_gray);
        page.setStrokeColor(pdf.Color.black);
        try page.setLineWidth(1);
        try page.drawFilledRect(80, 620, 40, 40);
        try page.setFont(.helvetica, 9);
        page.setFillColor(pdf.Color.dark_gray);
        try page.drawText(80, 600, "1.0x");

        // Scaled versions
        const scales = [_]struct { sx: f32, sy: f32, label: []const u8 }{
            .{ .sx = 1.5, .sy = 1.5, .label = "1.5x" },
            .{ .sx = 0.5, .sy = 0.5, .label = "0.5x" },
            .{ .sx = 2.0, .sy = 1.0, .label = "2x,1x" },
            .{ .sx = 1.0, .sy = 2.0, .label = "1x,2x" },
        };

        var x: f32 = 160;
        for (scales) |s| {
            try page.saveState();
            try page.scale(s.sx, s.sy, x + 20, 640);

            page.setFillColor(pdf.Color.rgb(100, 200, 150));
            page.setStrokeColor(pdf.Color.black);
            try page.drawFilledRect(x, 620, 40, 40);

            try page.restoreState();

            try page.setFont(.helvetica, 9);
            page.setFillColor(pdf.Color.dark_gray);
            try page.drawText(x, 600, s.label);

            x += 100;
        }

        // Skewing section
        try page.setFont(.helvetica_bold, 14);
        page.setFillColor(pdf.Color.black);
        try page.drawText(50, 540, "Skewing:");

        try page.setFont(.helvetica, 10);
        page.setFillColor(pdf.Color.dark_gray);
        try page.drawText(50, 520, "Skew (shear) graphics along X or Y axis");

        // Original
        page.setFillColor(pdf.Color.light_gray);
        page.setStrokeColor(pdf.Color.black);
        try page.drawFilledRect(80, 440, 50, 50);
        try page.setFont(.helvetica, 9);
        page.setFillColor(pdf.Color.dark_gray);
        try page.drawText(80, 420, "Original");

        // Skewed versions
        const skews = [_]struct { sx: f32, sy: f32, label: []const u8 }{
            .{ .sx = 15, .sy = 0, .label = "X: 15 deg" },
            .{ .sx = 30, .sy = 0, .label = "X: 30 deg" },
            .{ .sx = 0, .sy = 15, .label = "Y: 15 deg" },
            .{ .sx = 15, .sy = 15, .label = "XY: 15 deg" },
        };

        x = 170;
        for (skews) |s| {
            try page.saveState();
            try page.translate(x, 465);
            try page.skew(s.sx, s.sy);
            try page.translate(-x, -465);

            page.setFillColor(pdf.Color.rgb(200, 150, 100));
            page.setStrokeColor(pdf.Color.black);
            try page.drawFilledRect(x, 440, 50, 50);

            try page.restoreState();

            try page.setFont(.helvetica, 9);
            page.setFillColor(pdf.Color.dark_gray);
            try page.drawText(x, 420, s.label);

            x += 100;
        }

        // Combined transforms section
        try page.setFont(.helvetica_bold, 14);
        page.setFillColor(pdf.Color.black);
        try page.drawText(50, 360, "Combined Transforms:");

        try page.setFont(.helvetica, 10);
        page.setFillColor(pdf.Color.dark_gray);
        try page.drawText(50, 340, "Multiple transformations applied in sequence");

        // Example 1: Rotate + Scale
        try page.saveState();
        try page.rotate(30, 150, 260);
        try page.scale(1.5, 1.5, 150, 260);

        page.setFillColor(pdf.Color.rgb(255, 150, 150));
        page.setStrokeColor(pdf.Color.rgb(200, 0, 0));
        try page.setLineWidth(2);
        try page.drawFilledRect(120, 230, 60, 60);

        try page.restoreState();

        try page.setFont(.helvetica, 9);
        page.setFillColor(pdf.Color.dark_gray);
        try page.drawText(100, 170, "Rotate + Scale");

        // Example 2: Scale + Skew
        try page.saveState();
        try page.translate(300, 260);
        try page.skew(20, 0);
        try page.scaleFromOrigin(1.2, 0.8);
        try page.translate(-300, -260);

        page.setFillColor(pdf.Color.rgb(150, 255, 150));
        page.setStrokeColor(pdf.Color.rgb(0, 150, 0));
        try page.drawFilledRect(270, 230, 60, 60);

        try page.restoreState();

        try page.setFont(.helvetica, 9);
        page.setFillColor(pdf.Color.dark_gray);
        try page.drawText(250, 170, "Scale + Skew");

        // Example 3: Rotate + Skew + Scale
        try page.saveState();
        try page.rotate(-15, 450, 260);
        try page.translate(450, 260);
        try page.skew(10, 5);
        try page.scaleFromOrigin(1.3, 1.1);
        try page.translate(-450, -260);

        page.setFillColor(pdf.Color.rgb(150, 150, 255));
        page.setStrokeColor(pdf.Color.rgb(0, 0, 200));
        try page.drawFilledRect(420, 230, 60, 60);

        try page.restoreState();

        try page.setFont(.helvetica, 9);
        page.setFillColor(pdf.Color.dark_gray);
        try page.drawText(400, 170, "Rotate + Skew + Scale");

        // Footer
        try page.setFont(.helvetica, 9);
        page.setFillColor(pdf.Color.medium_gray);
        try page.drawText(250, 50, "Page 2 of 2 - zpdf Transforms Demo");
    }

    // Save
    const filename = "transforms_demo.pdf";
    try doc.save(filename);

    std.debug.print("Created: {s} ({d} pages)\n", .{ filename, doc.pageCount() });
    std.debug.print("Done!\n", .{});
}