package autofillcache

import (
	"encoding/json"
	"net/url"
	"os"
	"path/filepath"
	"sort"
	"strings"
	"time"

	"git.julianfamily.org/keepassgo/vault"
)

type Entry struct {
	ID       string   `json:"id"`
	Title    string   `json:"title"`
	Username string   `json:"username"`
	Password string   `json:"password"`
	URL      string   `json:"url"`
	Host     string   `json:"host"`
	Path     []string `json:"path,omitempty"`
}

type File struct {
	UpdatedAt string  `json:"updatedAt"`
	Entries   []Entry `json:"entries"`
}

func Match(cache File, webURL string) (Entry, bool) {
	target := normalizeURL(webURL)
	if target.host == "" {
		return Entry{}, false
	}

	exactHost := make([]Entry, 0)
	parentHost := make([]Entry, 0)
	for _, entry := range cache.Entries {
		if entry.Host == target.host {
			exactHost = append(exactHost, entry)
			continue
		}
		if entry.Host != "" && strings.HasSuffix(target.host, "."+entry.Host) {
			parentHost = append(parentHost, entry)
		}
	}

	if matched, ok := chooseEntry(target, exactHost); ok {
		return matched, true
	}
	return chooseEntry(target, parentHost)
}

func Build(model vault.Model, now time.Time) File {
	entries := make([]Entry, 0, len(model.Entries))
	for _, item := range model.Entries {
		host := normalizeHost(item.URL)
		if host == "" {
			continue
		}
		if strings.TrimSpace(item.Username) == "" || strings.TrimSpace(item.Password) == "" {
			continue
		}
		entries = append(entries, Entry{
			ID:       item.ID,
			Title:    item.Title,
			Username: item.Username,
			Password: item.Password,
			URL:      item.URL,
			Host:     host,
			Path:     append([]string(nil), item.Path...),
		})
	}
	return File{
		UpdatedAt: now.UTC().Format(time.RFC3339),
		Entries:   entries,
	}
}

func Write(path string, model vault.Model, now time.Time) error {
	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
		return err
	}
	data, err := json.MarshalIndent(Build(model, now), "", "  ")
	if err != nil {
		return err
	}
	return os.WriteFile(path, data, 0o600)
}

func Clear(path string) error {
	if err := os.Remove(path); err != nil && !os.IsNotExist(err) {
		return err
	}
	return nil
}

func normalizeHost(raw string) string {
	return normalizeURL(raw).host
}

type normalizedTarget struct {
	host string
	path string
	url  string
}

func normalizeURL(raw string) normalizedTarget {
	value := strings.TrimSpace(raw)
	if value == "" {
		return normalizedTarget{}
	}
	if !strings.Contains(value, "://") {
		value = "https://" + value
	}
	parsed, err := url.Parse(value)
	if err != nil {
		return normalizedTarget{}
	}
	host := strings.TrimSpace(parsed.Hostname())
	path := cleanPath(parsed.EscapedPath())
	return normalizedTarget{
		host: strings.ToLower(host),
		path: path,
		url:  strings.ToLower(host) + path,
	}
}

func cleanPath(path string) string {
	path = strings.TrimSpace(path)
	if path == "" || path == "/" {
		return "/"
	}
	path = strings.TrimRight(path, "/")
	if path == "" {
		return "/"
	}
	if !strings.HasPrefix(path, "/") {
		path = "/" + path
	}
	return path
}

func chooseEntry(target normalizedTarget, entries []Entry) (Entry, bool) {
	switch len(entries) {
	case 0:
		return Entry{}, false
	case 1:
		return entries[0], true
	}

	exact := make([]Entry, 0)
	prefix := make([]Entry, 0)
	for _, entry := range entries {
		entryTarget := normalizeURL(entry.URL)
		if entryTarget.host == "" {
			continue
		}
		if entryTarget.url == target.url {
			exact = append(exact, entry)
			continue
		}
		if entryTarget.path != "/" && strings.HasPrefix(target.path, entryTarget.path) {
			prefix = append(prefix, entry)
		}
	}
	if len(exact) == 1 {
		return exact[0], true
	}
	if len(exact) > 1 {
		return Entry{}, false
	}
	if len(prefix) == 0 {
		return Entry{}, false
	}

	sort.Slice(prefix, func(i, j int) bool {
		return len(normalizeURL(prefix[i].URL).path) > len(normalizeURL(prefix[j].URL).path)
	})
	bestPath := normalizeURL(prefix[0].URL).path
	best := make([]Entry, 0, len(prefix))
	for _, entry := range prefix {
		if normalizeURL(entry.URL).path == bestPath {
			best = append(best, entry)
		}
	}
	if len(best) == 1 {
		return best[0], true
	}
	return Entry{}, false
}