package choose_files

import (
	"cmp"
	"fmt"
	"os"
	"path/filepath"
	"regexp"
	"slices"
	"strings"
	"sync"

	"github.com/kovidgoyal/kitty/tools/tui/subseq"
	"github.com/kovidgoyal/kitty/tools/utils"
)

var _ = fmt.Print

type ResultItem struct {
	text, abspath string
	dir_entry     os.DirEntry
	positions     []int // may be nil
}

func (r ResultItem) String() string {
	return fmt.Sprintf("{text: %#v, abspath: %#v, is_dir: %v, positions: %#v}", r.text, r.abspath, r.dir_entry.IsDir(), r.positions)
}

type dir_cache map[string][]ResultItem

type ScanCache struct {
	dir_entries           dir_cache
	mutex                 sync.Mutex
	root_dir, search_text string
	in_progress           bool
	matches               []ResultItem
}

func (sc *ScanCache) get_cached_entries(root_dir string) (ans []ResultItem, found bool) {
	sc.mutex.Lock()
	defer sc.mutex.Unlock()
	ans, found = sc.dir_entries[root_dir]
	return
}

func (sc *ScanCache) set_cached_entries(root_dir string, e []ResultItem) {
	sc.mutex.Lock()
	defer sc.mutex.Unlock()
	sc.dir_entries[root_dir] = e
}

func scan_dir(path, root_dir string) []ResultItem {
	if ans, err := os.ReadDir(path); err == nil {
		if rel, err := filepath.Rel(root_dir, path); err == nil {
			return utils.Map(func(x os.DirEntry) ResultItem {
				path := filepath.Join(path, x.Name())
				r := filepath.Join(rel, x.Name())
				if root_dir == "/" {
					r = "/" + r
				}
				return ResultItem{dir_entry: x, abspath: path, text: r}
			}, ans)
		}
	}
	return []ResultItem{}
}

func is_excluded(path string, exclude_patterns []*regexp.Regexp) bool {
	for _, pattern := range exclude_patterns {
		if pattern.MatchString(path) {
			return true
		}
	}
	return false
}

func (sc *ScanCache) fs_scan(root_dir, current_dir string, max_depth int, exclude_patterns []*regexp.Regexp, seen map[string]bool) (ans []ResultItem) {
	var found bool
	if ans, found = sc.get_cached_entries(current_dir); !found {
		ans = scan_dir(current_dir, root_dir)
		sc.set_cached_entries(current_dir, ans)
	}
	ans = slices.Clone(ans)
	// now recurse into directories
	if max_depth > 0 {
		for _, x := range ans {
			if x.dir_entry.IsDir() && !seen[x.abspath] && !is_excluded(x.abspath, exclude_patterns) {
				seen[x.abspath] = true
				ans = append(ans, sc.fs_scan(root_dir, x.abspath, max_depth-1, exclude_patterns, seen)...)
			}
		}
	}
	return
}

func (sc *ScanCache) scan(root_dir, search_text string, max_depth int, exclude_patterns []*regexp.Regexp) (ans []ResultItem) {
	seen := make(map[string]bool, 1024)
	ans = sc.fs_scan(root_dir, root_dir, max_depth, exclude_patterns, seen)
	if search_text == "" {
		slices.SortFunc(ans, func(a, b ResultItem) int {
			switch a.dir_entry.IsDir() {
			case true:
				switch b.dir_entry.IsDir() {
				case true:
					return strings.Compare(strings.ToLower(a.text), strings.ToLower(b.text))
				case false:
					return -1
				}
			case false:
				switch b.dir_entry.IsDir() {
				case true:
					return 1
				case false:
					return strings.Compare(strings.ToLower(a.text), strings.ToLower(b.text))
				}
			}
			return 0
		})
	} else {
		pm := make(map[string]ResultItem, len(ans))
		for _, x := range ans {
			pm[x.text] = x
		}
		matches := utils.Filter(subseq.ScoreItems(search_text, utils.Keys(pm), subseq.Options{}), func(x *subseq.Match) bool {
			return x.Score > 0
		})
		slices.SortFunc(matches, func(a, b *subseq.Match) int { return cmp.Compare(b.Score, a.Score) })
		ans = utils.Map(func(m *subseq.Match) ResultItem {
			x := pm[m.Text]
			x.positions = m.Positions
			return x
		}, matches)
	}
	return ans
}

func (h *Handler) get_results() (ans []ResultItem, in_progress bool) {
	sc := &h.scan_cache
	sc.mutex.Lock()
	defer sc.mutex.Unlock()
	if sc.dir_entries == nil {
		sc.dir_entries = make(dir_cache, 512)
	}
	if sc.root_dir == h.state.CurrentDir() && sc.search_text == h.state.SearchText() {
		return sc.matches, sc.in_progress
	}
	sc.in_progress = true
	sc.matches = nil
	root_dir := h.state.CurrentDir()
	search_text := h.state.SearchText()
	sc.root_dir = root_dir
	sc.search_text = search_text
	go func() {
		results := sc.scan(root_dir, search_text, h.state.MaxDepth(), h.state.ExcludePatterns())
		sc.mutex.Lock()
		defer sc.mutex.Unlock()
		if root_dir == sc.root_dir && search_text == sc.search_text {
			sc.matches = results
			sc.in_progress = false
			h.lp.WakeupMainThread()
		}
	}()
	return sc.matches, sc.in_progress
}