#include <TCanvas.h>
#include <TH2D.h>
#include <TRandom.h>
#include <TStyle.h>

void fill_TH2D() {
	// Set style options
	gStyle->SetLineScalePS(1);

	gStyle->SetOptStat(0);            // Disable statistics box
	gStyle->SetPalette(kBird);        // Set color palette
	gStyle->SetNumberContours(999);   // Increase number of color contours
	gStyle->SetPadTopMargin(0.07);
	gStyle->SetPadBottomMargin(0.09);
	gStyle->SetPadLeftMargin(0.07);
	gStyle->SetPadRightMargin(0.13);

	// Create a 3x3 canvas with 2000x1200 resolution
	TCanvas *c1 = new TCanvas("c1", "3x3 Canvas with Histograms", 2000, 1200);
	c1->Divide(3, 3);

	// Random number generator
	TRandom rand;

	// Function to fill a single histogram
	auto fill_histogram = [&](TH2D *h2) {
		// Fill all bins along Y-axis for X in [-20, 20]
		for (int i = 0; i < 50000; i++) {
			double x = rand.Uniform(-20, 20); // Uniform distribution for X in [-20, 20]
			double y = rand.Gaus(50, 15);     // Gaussian for Y
			h2->Fill(x, y);
		}

		// Fill odd bins along Y-axis for X outside [-20, 20]
		for (int i = 0; i < 50000; i++) {
			// Fill the left X range [-40, -20)
			double x1 = -40 + rand.Landau(0, 5);
			if (x1 >= -40 && x1 < -20) {
				double y1 = rand.Gaus(50, 15);
				int ybin = h2->GetYaxis()->FindBin(y1);
				if (ybin % 2 != 0) { // Check if Y bin is odd
					h2->Fill(x1, y1);
				}
			}

			// Fill the right X range (20, 40]
			double x2 = 40 - rand.Landau(0, 5);
			if (x2 > 20 && x2 <= 40) {
				double y2 = rand.Gaus(50, 15);
				int ybin = h2->GetYaxis()->FindBin(y2);
				if (ybin % 2 != 0) { // Check if Y bin is odd
					h2->Fill(x2, y2);
				}
			}
		}
	};

	// Loop through the subpads and create histograms
	for (int i = 1; i <= 9; i++) {
		c1->cd(i);

		// Create a histogram for the subpad
		TH2D *h2 = new TH2D(
				Form("h2_%d", i),
				Form("Subpad %d Histogram;X-axis;Y-axis;Z-axis", i),
				80, -40, 40, 72, 0, 72);

		// Fill the histogram
		fill_histogram(h2);
		h2->GetYaxis()->SetTitleOffset(-1.0);
		h2->GetXaxis()->SetTitleOffset(-1.0);
		h2->GetXaxis()->SetLabelOffset(-0.05);
		h2->GetYaxis()->SetLabelOffset(-0.01);
		h2->GetXaxis()->SetTickSize(0.018);
		h2->GetYaxis()->SetTickSize(0.010);
		h2->GetXaxis()->SetTicks("-");
		h2->GetYaxis()->SetTicks("+");
		h2->Draw("COLZ");
	}

	// Save the canvas as PDF and PNG
	c1->SaveAs("th2d_histogram.pdf");
	c1->SaveAs("th2d_histogram.png");

	// Clean up
	delete c1;
}