package main

import (
	"errors"
	"fmt"
	"os"
	"path/filepath"
	"sort"
	"strings"
)

type FileEntry struct {
	path string

	size    *uint64
	modSize *uint64

	fileCount    *uint64
	modFileCount *uint64

	parent Entry

	removal bool
	noPerm  bool
	isMount bool
	isExec  bool
}

var _ Entry = &FileEntry{}

func (e *FileEntry) Name() string {
	return filepath.Base(e.path)
}

func (e *FileEntry) Path() string {
	return e.path
}

func (e *FileEntry) Size() uint64 {
	if e.size == nil {
		e.Scan(nil, nil)
	}

	return *e.size
}

func (e *FileEntry) Entries() []Entry {
	return []Entry{}
}

func (e *FileEntry) String() string {
	var ic string
	if e.isExec {
		ic = icon("app")
	} else {
		ic = icon(filepath.Ext(e.Path()))
	}

	if e.removal {
		return ColorRed.Sprintf(
			"%s %s (%s / %s)",
			ic, e.Name(), fmtSize(e.SizeModified()), fmtSize(e.Size()),
		)
	}

	if e.isExec {
		return ColorGreen.Sprintf("%s %s (%s)", ic, e.Name(), fmtSize(e.Size()))
	}

	return fmt.Sprintf("%s %s (%s)", ic, e.Name(), fmtSize(e.Size()))
}

func (e *FileEntry) stringRecursive(depth, maxDepth int, b *strings.Builder) {
	if depth > maxDepth {
		return
	}

	b.WriteString(strings.Repeat("  ", depth))
	b.WriteString(e.String())
	b.WriteRune('\n')
}

func (e *FileEntry) StringRecursive(depth int) string {
	b := new(strings.Builder)
	e.stringRecursive(0, depth, b)
	return b.String()
}

func (e *FileEntry) Scan(ch chan<- string, mounts map[string]struct{}) {
	if ch != nil {
		ch <- e.Path()
	}

	s := uint64(0)
	if fi, err := os.Lstat(e.Path()); err == nil {
		s = uint64(fi.Size())
		e.isExec = fi.Mode()&0x41 > 0 // 0x41 == 0b001000001 == rwXrwxrwX
	} else if errors.Is(err, os.ErrPermission) {
		e.noPerm = true
	}

	e.size = &s
	e.modSize = new(uint64)
	*e.modSize = *e.size

	f := uint64(1)
	e.fileCount = &f
	e.modFileCount = new(uint64)
	*e.modFileCount = *e.fileCount
}

func (e *FileEntry) Parent() Entry {
	return e.parent
}

func (e *FileEntry) Entry(path string) Entry {
	return e
}

func (e *FileEntry) IsDir() bool {
	return false
}

func (e *FileEntry) SetRemovalMark(mark bool) {
	e.removal = mark
	if mark {
		e.modify(-*e.size, -*e.fileCount) // underflow that is cancelling out perfectly
	} else {
		e.modify(*e.size, *e.fileCount)
	}

	// recalculate order of parent entries
	pentries := e.Parent().Entries()
	sort.Slice(pentries, func(i, j int) bool {
		return pentries[i].SizeModified() < pentries[j].SizeModified()
	})
}

func (e *FileEntry) RemovalMark() bool {
	return e.removal
}

func (e *FileEntry) SizeModified() uint64 {
	if e.size == nil {
		e.Size()
	}

	return *e.modSize
}

func (e *FileEntry) modify(size uint64, fileCount uint64) {
	*e.modSize = *e.modSize + size
	*e.modFileCount = *e.modFileCount + fileCount
	if e.parent != nil {
		e.parent.modify(size, fileCount)
	}
}

func (e *FileEntry) RemovalStats(stats *RemovalStats) {
	if e.RemovalMark() {
		stats.Files++
		stats.Bytes += *e.size
		if e.Parent() != nil && !e.Parent().RemovalMark() {
			stats.Paths = append(stats.Paths, e.Path())
		}
	}
}

func (e *FileEntry) FileCount() uint64 {
	return *e.fileCount
}

func (e *FileEntry) FileCountModified() uint64 {
	return *e.modFileCount
}