package handlers

import (
	"fmt"
	"net/http"

	"github.com/breakpilot/ai-compliance-sdk/internal/iace"
	"github.com/gin-gonic/gin"
	"github.com/google/uuid"
)

// ExportFMEA handles GET /projects/:id/fmea/export
// Returns an xlsx file in VDA FMEA format.
func (h *IACEHandler) ExportFMEA(c *gin.Context) {
	projectID, err := uuid.Parse(c.Param("id"))
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid project ID"})
		return
	}

	ctx := c.Request.Context()
	project, err := h.store.GetProject(ctx, projectID)
	if err != nil || project == nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "project not found"})
		return
	}

	// Load components
	components, _ := h.store.ListComponents(ctx, projectID)

	// Load all failure modes
	allFMs := iace.GetFailureModeLibrary()

	// Build FMEA rows: each component × matching FMs
	var rows []iace.FMEAExportRow
	for _, comp := range components {
		compType := string(comp.ComponentType)
		var compFMs []iace.FailureModeEntry
		for _, fm := range allFMs {
			if fm.ComponentType == compType {
				compFMs = append(compFMs, fm)
			}
		}
		if len(compFMs) == 0 {
			// Fallback: mechanical FMs
			for _, fm := range allFMs {
				if fm.ComponentType == "mechanical" && len(compFMs) < 3 {
					compFMs = append(compFMs, fm)
				}
			}
		}

		for _, fm := range compFMs {
			s, o, d := fm.DefaultSeverity, fm.DefaultOccurrence, fm.DefaultDetection
			rows = append(rows, iace.FMEAExportRow{
				ComponentName: comp.Name,
				ComponentType: compType,
				FailureMode:   fm.NameDE,
				FailureEffect: fm.Effect,
				FailureCause:  fm.DetectionHint,
				Severity:      s,
				Occurrence:    o,
				Detection:     d,
				RPZ:           s * o * d,
				AP:            iace.CalculateAP(s, o, d),
				Measure:       "",
				DetectionHint: fm.DetectionHint,
			})
		}
	}

	xlsxBytes, err := iace.GenerateFMEAExcel(project.MachineName, rows)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": fmt.Sprintf("Excel generation failed: %v", err)})
		return
	}

	filename := fmt.Sprintf("FMEA-%s.xlsx", project.MachineName)
	c.Header("Content-Disposition", fmt.Sprintf("attachment; filename=\"%s\"", filename))
	c.Data(http.StatusOK, "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet", xlsxBytes)
}