// Command inventory-go is a Go reimplementation of the MosswartOverlord
// inventory-service (FastAPI), deployed in parallel for comparison.
//
// Phase A: read side. Connects READ-ONLY to the existing inventory_db and
// reimplements the read endpoints, validated against the Python service on the
// same data. The heavy item-processing ingestion and the suitbuilder solver
// follow in later phases.
package main

import (
	"context"
	"encoding/json"
	"errors"
	"log/slog"
	"net/http"
	"os"
	"os/signal"
	"syscall"
	"time"

	"github.com/jackc/pgx/v5/pgxpool"
)

var buildVersion = "dev"

type Server struct {
	pool          *pgxpool.Pool
	attributeSets map[string]string // AttributeSetInfo: set-id -> set name
	log           *slog.Logger
}

func main() {
	logger := slog.New(slog.NewJSONHandler(os.Stdout, &slog.HandlerOptions{Level: slog.LevelInfo}))
	slog.SetDefault(logger)

	addr := ":" + envOr("PORT", "8772")
	dsn := os.Getenv("DATABASE_URL")
	enumPath := envOr("ENUM_DB_PATH", "comprehensive_enum_database_v2.json")
	readOnly := envOr("READ_ONLY", "true") != "false"

	logger.Info("starting inventory-go", "version", buildVersion, "addr", addr, "read_only", readOnly)

	ctx, stop := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
	defer stop()

	srv := &Server{log: logger, attributeSets: map[string]string{}}

	if sets, err := loadAttributeSets(enumPath); err != nil {
		logger.Warn("could not load enum AttributeSetInfo (set names will be unknown)", "err", err, "path", enumPath)
	} else {
		srv.attributeSets = sets
		logger.Info("loaded enum AttributeSetInfo", "sets", len(sets))
	}

	if dsn == "" {
		logger.Error("DATABASE_URL is required")
		os.Exit(1)
	}
	connectCtx, cancel := context.WithTimeout(ctx, 15*time.Second)
	pool, err := newPool(connectCtx, dsn, readOnly)
	cancel()
	if err != nil {
		logger.Error("db pool init failed", "err", err)
		os.Exit(1)
	}
	defer pool.Close()
	srv.pool = pool

	mux := http.NewServeMux()
	mux.HandleFunc("GET /health", srv.handleHealth)
	mux.HandleFunc("GET /sets/list", srv.handleSetsList)
	mux.HandleFunc("GET /characters/list", srv.handleCharactersList)

	httpSrv := &http.Server{Addr: addr, Handler: withLogging(mux), ReadHeaderTimeout: 10 * time.Second}
	go func() {
		if err := httpSrv.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
			logger.Error("http server failed", "err", err)
			os.Exit(1)
		}
	}()
	logger.Info("listening", "addr", addr)

	<-ctx.Done()
	shutdownCtx, c := context.WithTimeout(context.Background(), 10*time.Second)
	defer c()
	_ = httpSrv.Shutdown(shutdownCtx)
	logger.Info("stopped")
}

// GET /health (main.py:2674)
func (s *Server) handleHealth(w http.ResponseWriter, r *http.Request) {
	ctx, cancel := context.WithTimeout(r.Context(), 3*time.Second)
	defer cancel()
	dbOK := s.pool.Ping(ctx) == nil
	status := "healthy"
	if !dbOK {
		status = "degraded"
	}
	writeJSON(w, http.StatusOK, map[string]any{
		"status":             status,
		"timestamp":          pyISO(time.Now()),
		"database_connected": dbOK,
		"version":            "1.0.0",
	})
}

// GET /sets/list (main.py:2712)
func (s *Server) handleSetsList(w http.ResponseWriter, r *http.Request) {
	ctx, cancel := context.WithTimeout(r.Context(), 15*time.Second)
	defer cancel()
	rows, err := queryRowsAsMaps(ctx, s.pool, `
		SELECT enh.item_set, COUNT(*) AS item_count
		FROM item_enhancements enh
		WHERE enh.item_set IS NOT NULL AND enh.item_set != ''
		GROUP BY enh.item_set
		ORDER BY item_count DESC, enh.item_set`)
	if err != nil {
		s.dbErr(w, "sets/list", err)
		return
	}
	sets := make([]map[string]any, 0, len(rows))
	for _, row := range rows {
		setID := toStr(row["item_set"])
		name, ok := s.attributeSets[setID]
		if !ok {
			name = "Unknown Set " + setID
		}
		sets = append(sets, map[string]any{"id": setID, "name": name, "item_count": row["item_count"]})
	}
	writeJSON(w, http.StatusOK, map[string]any{"sets": sets})
}

// GET /characters/list (main.py:4291)
func (s *Server) handleCharactersList(w http.ResponseWriter, r *http.Request) {
	ctx, cancel := context.WithTimeout(r.Context(), 15*time.Second)
	defer cancel()
	rows, err := queryRowsAsMaps(ctx, s.pool, `
		SELECT character_name, COUNT(*) AS item_count, MAX(timestamp) AS last_updated
		FROM items GROUP BY character_name ORDER BY character_name`)
	if err != nil {
		s.dbErr(w, "characters/list", err)
		return
	}
	formatTimes(rows, "last_updated")
	chars := make([]map[string]any, 0, len(rows))
	for _, row := range rows {
		chars = append(chars, map[string]any{
			"character_name": row["character_name"],
			"item_count":     row["item_count"],
			"last_updated":   row["last_updated"],
		})
	}
	writeJSON(w, http.StatusOK, map[string]any{"characters": chars, "total_characters": len(chars)})
}

func (s *Server) dbErr(w http.ResponseWriter, where string, err error) {
	s.log.Error("db query failed", "where", where, "err", err)
	writeJSON(w, http.StatusInternalServerError, map[string]any{"detail": "Internal server error"})
}

// loadAttributeSets reads the comprehensive enum DB and extracts AttributeSetInfo
// (set-id -> name), mirroring load_comprehensive_enums (dictionaries first, then
// enums). Only the slice needed for /sets/list is decoded.
func loadAttributeSets(path string) (map[string]string, error) {
	b, err := os.ReadFile(path)
	if err != nil {
		return nil, err
	}
	var db struct {
		Dictionaries map[string]struct {
			Values map[string]string `json:"values"`
		} `json:"dictionaries"`
		Enums map[string]struct {
			Values map[string]string `json:"values"`
		} `json:"enums"`
	}
	if err := json.Unmarshal(b, &db); err != nil {
		return nil, err
	}
	if d, ok := db.Dictionaries["AttributeSetInfo"]; ok && len(d.Values) > 0 {
		return d.Values, nil
	}
	if e, ok := db.Enums["AttributeSetInfo"]; ok {
		return e.Values, nil
	}
	return map[string]string{}, nil
}

func envOr(key, def string) string {
	if v := os.Getenv(key); v != "" {
		return v
	}
	return def
}

func withLogging(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		start := time.Now()
		next.ServeHTTP(w, r)
		slog.Info("http", "method", r.Method, "path", r.URL.Path, "dur_ms", time.Since(start).Milliseconds())
	})
}