package webui

import (
	"embed"
	"encoding/json"
	"fmt"
	"io/fs"
	"net/http"
	"os"
	"sort"
	"strings"

	"scrappr/internal/logx"
	"scrappr/internal/model"
)

//go:embed static/*
var staticFiles embed.FS

type Catalog struct {
	ItemNames  []string         `json:"item_names"`
	Items      []CatalogItem    `json:"items"`
	Craftables []CraftableEntry `json:"craftables"`
}

type CatalogItem struct {
	Name       string         `json:"name"`
	URL        string         `json:"url"`
	ImageURL   string         `json:"image_url,omitempty"`
	Categories []string       `json:"categories,omitempty"`
	ItemType   string         `json:"item_type,omitempty"`
}

type CraftableEntry struct {
	CatalogItem
	Recipes    []model.Recipe `json:"recipes"`
}

func Run(addr, dataPath string) error {
	catalog, err := loadCatalog(dataPath)
	if err != nil {
		return err
	}

	staticFS, err := fs.Sub(staticFiles, "static")
	if err != nil {
		return err
	}

	mux := http.NewServeMux()
	mux.HandleFunc("/", serveStaticFile(staticFS, "index.html", "text/html; charset=utf-8"))
	mux.HandleFunc("/styles.css", serveStaticFile(staticFS, "styles.css", "text/css; charset=utf-8"))
	mux.HandleFunc("/app.js", serveStaticFile(staticFS, "app.js", "application/javascript; charset=utf-8"))
	mux.HandleFunc("/api/catalog", func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodGet {
			http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
			return
		}

		setNoCache(w)
		w.Header().Set("Content-Type", "application/json; charset=utf-8")
		if err := json.NewEncoder(w).Encode(catalog); err != nil {
			logx.Eventf("error", "catalog encode failed: %v", err)
		}
	})

	logx.Eventf(
		"start",
		"web UI listening on %s using %s (%d craftable items)",
		displayAddr(addr),
		dataPath,
		len(catalog.Craftables),
	)

	return http.ListenAndServe(addr, mux)
}

func loadCatalog(dataPath string) (Catalog, error) {
	file, err := os.Open(dataPath)
	if err != nil {
		return Catalog{}, fmt.Errorf("open dataset %s: %w", dataPath, err)
	}
	defer file.Close()

	var dataset model.Dataset
	if err := json.NewDecoder(file).Decode(&dataset); err != nil {
		return Catalog{}, fmt.Errorf("decode dataset %s: %w", dataPath, err)
	}

	return buildCatalog(dataset), nil
}

func buildCatalog(dataset model.Dataset) Catalog {
	itemNames := make([]string, 0, len(dataset.Items))
	items := make([]CatalogItem, 0, len(dataset.Items))
	craftableByName := map[string]*CraftableEntry{}
	itemByName := map[string]CatalogItem{}
	seen := map[string]bool{}

	for _, item := range dataset.Items {
		name := strings.TrimSpace(item.Name)
		if name != "" && !seen[name] {
			seen[name] = true
			itemNames = append(itemNames, name)
		}

		catalogItem := CatalogItem{
			Name:       item.Name,
			URL:        item.URL,
			ImageURL:   item.ImageURL,
			Categories: item.Categories,
			ItemType:   item.Infobox["Type"],
		}

		items = append(items, catalogItem)
		itemByName[strings.ToLower(strings.TrimSpace(item.Name))] = catalogItem
	}

	for _, item := range dataset.Items {
		for _, recipe := range item.Recipes {
			resultKey := strings.ToLower(strings.TrimSpace(recipe.Result))
			if resultKey == "" {
				continue
			}

			entry := craftableByName[resultKey]
			if entry == nil {
				base := itemByName[resultKey]
				if strings.TrimSpace(base.Name) == "" {
					base = CatalogItem{
						Name:     recipe.Result,
						URL:      item.URL,
						ImageURL: item.ImageURL,
					}
				}

				entry = &CraftableEntry{
					CatalogItem: base,
				}
				craftableByName[resultKey] = entry
			}

			if !hasRecipe(entry.Recipes, recipe) {
				entry.Recipes = append(entry.Recipes, recipe)
			}
		}
	}

	sort.Strings(itemNames)
	sort.Slice(items, func(i, j int) bool {
		return strings.ToLower(items[i].Name) < strings.ToLower(items[j].Name)
	})

	craftables := make([]CraftableEntry, 0, len(craftableByName))
	for _, entry := range craftableByName {
		craftables = append(craftables, *entry)
	}
	sort.Slice(craftables, func(i, j int) bool {
		return strings.ToLower(craftables[i].Name) < strings.ToLower(craftables[j].Name)
	})

	return Catalog{
		ItemNames:  itemNames,
		Items:      items,
		Craftables: craftables,
	}
}

func hasRecipe(existing []model.Recipe, target model.Recipe) bool {
	for _, recipe := range existing {
		if recipe.Result != target.Result || recipe.ResultCount != target.ResultCount || recipe.Station != target.Station {
			continue
		}
		if len(recipe.Ingredients) != len(target.Ingredients) {
			continue
		}

		match := true
		for i := range recipe.Ingredients {
			if recipe.Ingredients[i] != target.Ingredients[i] {
				match = false
				break
			}
		}

		if match {
			return true
		}
	}

	return false
}

func displayAddr(addr string) string {
	if strings.HasPrefix(addr, ":") {
		return "http://localhost" + addr
	}
	if strings.HasPrefix(addr, "http://") || strings.HasPrefix(addr, "https://") {
		return addr
	}
	return "http://" + addr
}

func serveStaticFile(staticFS fs.FS, name, contentType string) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		if r.URL.Path != "/" && "/"+name != r.URL.Path {
			http.NotFound(w, r)
			return
		}

		content, err := fs.ReadFile(staticFS, name)
		if err != nil {
			http.Error(w, "asset missing", http.StatusInternalServerError)
			return
		}

		setNoCache(w)
		w.Header().Set("Content-Type", contentType)
		_, _ = w.Write(content)
	}
}

func setNoCache(w http.ResponseWriter) {
	w.Header().Set("Cache-Control", "no-store, no-cache, must-revalidate")
	w.Header().Set("Pragma", "no-cache")
	w.Header().Set("Expires", "0")
}