package web

import (
	"errors"
	"fmt"
	"net/url"
	"sort"
)

type fileMap map[string]string

var errInvalidPasteForm = errors.New("invalid map of filenames to filenames")

type indexFileMapping struct {
	indices   []int
	filenames []string
}

func (m *indexFileMapping) insert(index int, filename string) {
	m.indices = append(m.indices, index)
	m.filenames = append(m.filenames, filename)
}

func (m *indexFileMapping) Len() int {
	if len(m.indices) != len(m.filenames) {
		panic("indices and filenames do not map one to one")
	}

	return len(m.indices)
}

func (m *indexFileMapping) Less(i, j int) bool {
	return m.indices[i] < m.indices[j]
}

func (m *indexFileMapping) Swap(i, j int) {
	m.indices[i], m.indices[j] = m.indices[j], m.indices[i]
	m.filenames[i], m.filenames[j] = m.filenames[j], m.filenames[i]
}

// Returns a map of the files and an ordered list of the files
func makeFileMap(formData url.Values) (fileMap, []string, error) {
	fileMap := make(fileMap)
	filenames, err := makeOrderedFilenameList(formData)
	if err != nil {
		return nil, nil, err
	}

	for formKey, formValue := range formData {
		if len(formValue) != 1 {
			fmt.Println("here")
			return nil, nil, errInvalidPasteForm
		}

		var fileIndex int
		n, err := fmt.Sscanf(formKey, fileNameFormKey+"%d", &fileIndex)
		if n == 0 || err != nil {
			// We aren't looking at a file name key in this case
			continue
		}
		filename := formValue[0]
		bodyKey := fmt.Sprintf("%s%d", bodyFormKey, fileIndex)
		fmt.Println(bodyKey)
		bodyEntry, haveBody := formData[bodyKey]
		if !haveBody || len(bodyEntry) != 1 {
			fmt.Println("here2")
			return nil, nil, errInvalidPasteForm
		}

		fileMap[filename] = bodyEntry[0]
	}

	return fileMap, filenames, nil
}

func makeOrderedFilenameList(formData url.Values) ([]string, error) {
	indicesToFiles := indexFileMapping{
		indices:   make([]int, 0),
		filenames: make([]string, 0),
	}

	for formKey, formValue := range formData {
		if len(formValue) != 1 {
			fmt.Println("here3")
			return nil, errInvalidPasteForm
		}

		var fileIndex int
		n, err := fmt.Sscanf(formKey, fileNameFormKey+"%d", &fileIndex)
		if n == 0 || err != nil {
			// We aren't looking at a file name key in this case
			continue
		}
		indicesToFiles.insert(fileIndex, formValue[0])
	}

	sort.Sort(&indicesToFiles)

	return indicesToFiles.filenames, nil
}