package app

import (
	"encoding/json"
	"io"
	"io/fs"
	"net/http"
	"os"
	"path/filepath"
	"strings"
)

// ---------------------------------------------------------------------
// domains file
// ---------------------------------------------------------------------

// GET /api/v1/domains/file?name=bases|meta|subs|static|smartdns|last-ips-map|last-ips-map-direct|last-ips-map-wildcard|wildcard-observed-hosts
// POST /api/v1/domains/file { "name": "...", "content": "..." }
func handleDomainsFile(w http.ResponseWriter, r *http.Request) {
	switch r.Method {
	case http.MethodGet:
		name := strings.TrimSpace(r.URL.Query().Get("name"))
		if name == "smartdns" {
			domains, source := loadSmartDNSWildcardDomainsState(nil)
			writeJSON(w, http.StatusOK, map[string]string{
				"content": renderSmartDNSDomainsContent(domains),
				"source":  source,
			})
			return
		}
		if name == "wildcard-observed-hosts" {
			writeJSON(w, http.StatusOK, map[string]string{
				"content": readWildcardObservedHostsContent(),
				"source":  "derived",
			})
			return
		}
		path, ok := domainFiles[name]
		if !ok {
			http.Error(w, "unknown file name", http.StatusBadRequest)
			return
		}
		source := "file"
		if strings.HasPrefix(name, "last-ips-map") {
			source = "artifact"
		}
		data, err := os.ReadFile(path)
		if err != nil {
			if !os.IsNotExist(err) {
				http.Error(w, "read error", http.StatusInternalServerError)
				return
			}
			switch name {
			case "bases", "meta", "subs":
				// fallback to embedded seed
				embedName := name + ".txt"
				if name == "meta" {
					embedName = "meta-special.txt"
				}
				data, _ = fs.ReadFile(embeddedDomains, "assets/domains/"+embedName)
				source = "embedded"
			default:
				data = []byte{}
			}
		}
		writeJSON(w, http.StatusOK, map[string]string{
			"content": string(data),
			"source":  source,
		})
	case http.MethodPost:
		var body struct {
			Name    string `json:"name"`
			Content string `json:"content"`
		}
		if r.Body != nil {
			defer r.Body.Close()
			if err := json.NewDecoder(io.LimitReader(r.Body, 1<<20)).Decode(&body); err != nil {
				http.Error(w, "bad json", http.StatusBadRequest)
				return
			}
		}
		if strings.TrimSpace(body.Name) == "smartdns" {
			domains := parseSmartDNSDomainsContent(body.Content)
			if err := saveSmartDNSWildcardDomainsState(domains); err != nil {
				http.Error(w, "write error", http.StatusInternalServerError)
				return
			}
			writeJSON(w, http.StatusOK, map[string]string{"status": "ok"})
			return
		}
		if body.Name == "last-ips-map-direct" || body.Name == "last-ips-map-wildcard" || body.Name == "wildcard-observed-hosts" {
			http.Error(w, "read-only file name", http.StatusBadRequest)
			return
		}
		path, ok := domainFiles[strings.TrimSpace(body.Name)]
		if !ok {
			http.Error(w, "unknown file name", http.StatusBadRequest)
			return
		}
		_ = os.MkdirAll(filepath.Dir(path), 0o755)
		if err := os.WriteFile(path, []byte(body.Content), 0o644); err != nil {
			http.Error(w, "write error", http.StatusInternalServerError)
			return
		}
		writeJSON(w, http.StatusOK, map[string]string{"status": "ok"})
	default:
		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
	}
}