package format

import (
	"fmt"
	"sort"
	"strings"
)

type importItem struct {
	Comment string
	Name    string
	Path    string
}

func (ii importItem) String() string {
	var comment string
	if ii.Comment != "" {
		comment = ii.Comment + "\n\t"
	}
	var name string
	if ii.Name != "" {
		name = ii.Name + " "
	}
	return comment + name + ii.Path
}

type importBlock struct {
	Stdlib []importItem
	Module []importItem
	Other  []importItem
}

func importItemSlice(ii []importItem) []string {
	iis := make([]string, 0, len(ii))
	for _, i := range ii {
		iis = append(iis, i.String())
	}
	return iis
}

func (i importBlock) String() string {
	var decl strings.Builder

	decl.WriteString(strings.Join(importItemSlice(i.Stdlib), "\n\t"))
	if len(i.Module) > 0 {
		decl.WriteString("\n\n\t")
	}
	decl.WriteString(strings.Join(importItemSlice(i.Module), "\n\t"))
	if len(i.Other) > 0 {
		decl.WriteString("\n\n\t")
	}
	decl.WriteString(strings.Join(importItemSlice(i.Other), "\n\t"))

	return fmt.Sprintf(`import (
	%s
)`, decl.String())
}

func parseBlock(module string, imports []string) importBlock {
	var block importBlock
	var comment string
	for _, imp := range imports {
		if imp == "" {
			continue
		}
		i := imp
		if strings.HasPrefix(i, `//`) {
			var nl string
			if comment != "" {
				nl = "\n"
			}
			comment = nl + i
			continue
		}

		var name string
		if !strings.HasPrefix(i, `"`) {
			parts := strings.SplitN(i, " ", 2)
			name = parts[0]
			i = parts[1]
		}
		item := importItem{
			Comment: comment,
			Name:    name,
			Path:    i,
		}
		switch {
		case strings.Contains(i, module):
			block.Module = append(block.Module, item)
		case strings.Contains(i, "."):
			block.Other = append(block.Other, item)
		default:
			block.Stdlib = append(block.Stdlib, item)
		}
		comment = ""
	}

	fn := func(ii []importItem) func(int, int) bool {
		return func(i, j int) bool {
			return ii[i].Path < ii[j].Path
		}
	}
	sort.Slice(block.Stdlib, fn(block.Stdlib))
	sort.Slice(block.Module, fn(block.Module))
	sort.Slice(block.Other, fn(block.Other))
	return block
}