package libreoffice

import (
	"errors"
	"fmt"
	"net/http"

	"github.com/labstack/echo/v4"

	"github.com/gotenberg/gotenberg/v7/pkg/gotenberg"
	"github.com/gotenberg/gotenberg/v7/pkg/modules/api"
	libreofficeapi "github.com/gotenberg/gotenberg/v7/pkg/modules/libreoffice/api"
)

// convertRoute returns an [api.Route] which can convert LibreOffice documents
// to PDF.
func convertRoute(libreOffice libreofficeapi.Uno, engine gotenberg.PdfEngine) api.Route {
	return api.Route{
		Method:      http.MethodPost,
		Path:        "/forms/libreoffice/convert",
		IsMultipart: true,
		Handler: func(c echo.Context) error {
			ctx := c.Get("context").(*api.Context)

			// Let's get the data from the form and validate them.
			var (
				inputPaths         []string
				landscape          bool
				nativePageRanges   string
				nativePdfA1aFormat bool
				nativePdfFormat    string
				pdfFormat          string
				pdfa               string
				pdfua              bool
				nativePdfFormats   bool
				merge              bool
			)

			err := ctx.FormData().
				MandatoryPaths(libreOffice.Extensions(), &inputPaths).
				Bool("landscape", &landscape, false).
				String("nativePageRanges", &nativePageRanges, "").
				Bool("nativePdfA1aFormat", &nativePdfA1aFormat, false).
				String("nativePdfFormat", &nativePdfFormat, "").
				String("pdfFormat", &pdfFormat, "").
				String("pdfa", &pdfa, "").
				Bool("pdfua", &pdfua, false).
				Bool("nativePdfFormats", &nativePdfFormats, true).
				Bool("merge", &merge, false).
				Validate()
			if err != nil {
				return fmt.Errorf("validate form data: %w", err)
			}

			// FIXME: deprecated.
			// pdfa > nativePdfFormat > pdfFormat > nativePdfA1aFormat.
			var (
				actualPdfArchive string
				nativeFormats    bool
			)

			if nativePdfA1aFormat {
				ctx.Log().Warn("'nativePdfA1aFormat' is deprecated; prefer the 'pdfa' form field instead")
				actualPdfArchive = gotenberg.PdfA1a
				nativeFormats = true
			}

			if pdfFormat != "" {
				ctx.Log().Warn("'pdfFormat' is deprecated; prefer the 'pdfa' form field instead")
				actualPdfArchive = pdfFormat
				nativeFormats = false
			}

			if nativePdfFormat != "" {
				ctx.Log().Warn("'nativePdfFormat' is deprecated; prefer the 'pdfa' form field instead")
				actualPdfArchive = nativePdfFormat
				nativeFormats = true
			}

			if pdfa != "" {
				actualPdfArchive = pdfa
				nativeFormats = nativePdfFormats
			}

			if pdfua {
				nativeFormats = nativePdfFormats
			}

			pdfFormats := gotenberg.PdfFormats{
				PdfA:  actualPdfArchive,
				PdfUa: pdfua,
			}

			// Alright, let's convert each document to PDF.
			outputPaths := make([]string, len(inputPaths))
			for i, inputPath := range inputPaths {
				outputPaths[i] = ctx.GeneratePath(".pdf")

				options := libreofficeapi.Options{
					Landscape:  landscape,
					PageRanges: nativePageRanges,
				}

				if nativeFormats {
					options.PdfFormats = pdfFormats
				}

				err = libreOffice.Pdf(ctx, ctx.Log(), inputPath, outputPaths[i], options)
				if err != nil {
					if errors.Is(err, libreofficeapi.ErrMalformedPageRanges) {
						return api.WrapError(
							fmt.Errorf("convert to PDF: %w", err),
							api.NewSentinelHTTPError(http.StatusBadRequest, fmt.Sprintf("Malformed page ranges '%s' (nativePageRanges)", options.PageRanges)),
						)
					}

					return fmt.Errorf("convert to PDF: %w", err)
				}
			}

			// So far so good, let's check if we have to merge the PDFs. Quick
			// win: if there is only one PDF, skip this step.

			if len(outputPaths) > 1 && merge {
				outputPath := ctx.GeneratePath(".pdf")

				err = engine.Merge(ctx, ctx.Log(), outputPaths, outputPath)
				if err != nil {
					return fmt.Errorf("merge PDFs: %w", err)
				}

				// Now, let's check if the client want to convert this result
				// PDF to specific PDF formats.
				zeroValued := gotenberg.PdfFormats{}
				if !nativeFormats && pdfFormats != zeroValued {
					convertInputPath := outputPath
					convertOutputPath := ctx.GeneratePath(".pdf")

					err = engine.Convert(ctx, ctx.Log(), pdfFormats, convertInputPath, convertOutputPath)
					if err != nil {
						if errors.Is(err, gotenberg.ErrPdfFormatNotSupported) {
							return api.WrapError(
								fmt.Errorf("convert PDF: %w", err),
								api.NewSentinelHTTPError(
									http.StatusBadRequest,
									fmt.Sprintf("At least one PDF engine does not handle one of the PDF format in '%+v', while other have failed to convert for other reasons", pdfFormats),
								),
							)
						}

						return fmt.Errorf("convert PDF: %w", err)
					}

					// Important: the output path is now the converted file.
					outputPath = convertOutputPath
				}

				// Last but not least, add the output path to the context so that
				// the Uno is able to send it as a response to the client.

				err = ctx.AddOutputPaths(outputPath)
				if err != nil {
					return fmt.Errorf("add output path: %w", err)
				}

				return nil
			}

			// Ok, we don't have to merge the PDFs. Let's check if the client
			// want to convert each PDF to a specific PDF format.
			zeroValued := gotenberg.PdfFormats{}
			if !nativeFormats && pdfFormats != zeroValued {
				convertOutputPaths := make([]string, len(outputPaths))

				for i, outputPath := range outputPaths {
					convertInputPath := outputPath
					convertOutputPaths[i] = ctx.GeneratePath(".pdf")

					err = engine.Convert(ctx, ctx.Log(), pdfFormats, convertInputPath, convertOutputPaths[i])
					if err != nil {
						if errors.Is(err, gotenberg.ErrPdfFormatNotSupported) {
							return api.WrapError(
								fmt.Errorf("convert PDF: %w", err),
								api.NewSentinelHTTPError(
									http.StatusBadRequest,
									fmt.Sprintf("At least one PDF engine does not handle one of the PDF format in '%+v', while other have failed to convert for other reasons", pdfFormats),
								),
							)
						}

						return fmt.Errorf("convert PDF: %w", err)
					}

				}

				// Important: the output paths are now the converted files.
				outputPaths = convertOutputPaths
			}

			// Last but not least, add the output paths to the context so that
			// the Uno is able to send them as a response to the client.

			err = ctx.AddOutputPaths(outputPaths...)
			if err != nil {
				return fmt.Errorf("add output paths: %w", err)
			}

			return nil
		},
	}
}