using PuppeteerSharp;
using PuppeteerSharp.Media;

namespace GB5Shared.Export.HybridReport
{
    public class PdfRenderer
    {
        public async Task<byte[]> RenderToPdfBytesAsync(string html, IDictionary<string, object>? metadata = null)
        {
            // Reuse the shared, already-launched browser instead of launching a fresh Chromium
            // process per call — GlobalBrowser already resolves the executable via
            // ChromiumResolver and recovers if the cached instance crashed/disconnected.
            var browser = await GlobalBrowser.GetAsync().ConfigureAwait(false);
            await using var page = await browser.NewPageAsync();
            await page.SetContentAsync(html, new NavigationOptions
            {
                WaitUntil = new[] { WaitUntilNavigation.Networkidle0 }
            });

            // Force scaling in browser DOM before printing
            await page.EvaluateFunctionAsync(@"() => {
                const page = document.getElementById('pageContainer');
                const wrapper = document.getElementById('tableWrapper');
                if (!page || !wrapper) return;

                const pageWidth = page.clientWidth * 0.96;
                const tableWidth = wrapper.scrollWidth;
                if (tableWidth <= 0) return;

                let scale = pageWidth / tableWidth;
                if (scale > 1.12) scale = 1.12;
                if (scale < 0.75) scale = 0.75;

                wrapper.style.transform = `scale(${scale})`;
                wrapper.style.transformOrigin = 'top center';
                const scaledWidth = tableWidth * scale;
                const offset = (page.clientWidth - scaledWidth) / 2;
                wrapper.style.marginLeft = offset > 0 ? `${offset}px` : '0';
            }");

            // Header/Footer templates
            string headerTemplate = metadata != null && metadata.ContainsKey("headerTemplate")
                ? metadata["headerTemplate"]?.ToString() ?? string.Empty
                : string.Empty;

            string footerTemplate = metadata != null && metadata.ContainsKey("footerTemplate")
                ? metadata["footerTemplate"]?.ToString() ??
                  "Page <span class='pageNumber'></span> of <span class='totalPages'></span>"
                : "Page <span class='pageNumber'></span> of <span class='totalPages'></span>";

            var pdfOptions = new PdfOptions
            {
                Format = PaperFormat.A4,
                PrintBackground = true,
                DisplayHeaderFooter = true,
                HeaderTemplate = headerTemplate,
                FooterTemplate = footerTemplate,
                MarginOptions = new MarginOptions
                {
                    Top = "80px",
                    Left = "0px",
                    Right = "20px"
                }
            };

            await using var pdfStream = await page.PdfStreamAsync(pdfOptions);
            using var ms = new MemoryStream();
            await pdfStream.CopyToAsync(ms);
            return ms.ToArray();
        }

        public static async Task<byte[]> RenderHtmlToPdfAsync(string html, IDictionary<string, object>? metadata = null)
        {
            var renderer = new PdfRenderer();
            return await renderer.RenderToPdfBytesAsync(html, metadata);
        }
    }
}