package statuses

import (
	"context"
	"encoding/csv"
	"fmt"
	"io"
	"strings"

	"inventree/internal/models"
)

type ImportResult struct {
	Created int
	Updated int
	Errors  []string
}

// Import creates or updates statuses from CSV data with "Name" and "Color"
// columns (case-insensitive header names, Color optional). Existing
// statuses are matched and updated by name (case-insensitive); everything
// else is created.
func (s *Store) Import(ctx context.Context, r io.Reader) (*ImportResult, error) {
	existing, err := s.List(ctx)
	if err != nil {
		return nil, err
	}
	byName := map[string]int64{}
	for _, st := range existing {
		byName[strings.ToLower(st.Name)] = st.ID
	}

	cr := csv.NewReader(r)
	cr.FieldsPerRecord = -1
	header, err := cr.Read()
	if err != nil {
		if err == io.EOF {
			return &ImportResult{}, nil
		}
		return nil, fmt.Errorf("read CSV header: %w", err)
	}
	colIdx := map[string]int{}
	for i, h := range header {
		colIdx[strings.ToLower(strings.TrimSpace(h))] = i
	}
	get := func(row []string, key string) string {
		idx, ok := colIdx[key]
		if !ok || idx >= len(row) {
			return ""
		}
		return strings.TrimSpace(row[idx])
	}

	result := &ImportResult{}
	rowNum := 1
	for {
		row, err := cr.Read()
		if err == io.EOF {
			break
		}
		if err != nil {
			return nil, fmt.Errorf("read CSV row %d: %w", rowNum, err)
		}
		rowNum++

		name := get(row, "name")
		if name == "" {
			result.Errors = append(result.Errors, fmt.Sprintf("row %d: name is required, skipped", rowNum))
			continue
		}
		color := get(row, "color")

		if id, ok := byName[strings.ToLower(name)]; ok {
			st, err := s.Get(ctx, id)
			if err != nil {
				result.Errors = append(result.Errors, fmt.Sprintf("row %d: %v", rowNum, err))
				continue
			}
			if color != "" {
				st.Color = color
			}
			if err := s.Update(ctx, st); err != nil {
				result.Errors = append(result.Errors, fmt.Sprintf("row %d: update failed: %v", rowNum, err))
				continue
			}
			result.Updated++
			continue
		}

		st := &models.Status{Name: name, Color: color}
		if err := s.Create(ctx, st); err != nil {
			result.Errors = append(result.Errors, fmt.Sprintf("row %d: create failed: %v", rowNum, err))
			continue
		}
		byName[strings.ToLower(name)] = st.ID
		result.Created++
	}
	return result, nil
}