package main

import (
	"context"
	"encoding/json"
	"flag"
	"fmt"
	"log"
	"os"
	"os/signal"
	"syscall"

	"bugs.watch/agent/internal/agent"
	"bugs.watch/agent/internal/config"
	"bugs.watch/agent/internal/dbmanager"
)

func main() {
	// Peek at the first arg before flag parsing to detect sub-commands.
	if len(os.Args) > 1 && os.Args[1] == "db" {
		runDBCmd(os.Args[2:])
		return
	}

	cfg, err := config.Load()
	if err != nil {
		log.Fatalf("configuration error: %v", err)
	}

	flag.StringVar(&cfg.DBConfigPath, "db-config", cfg.DBConfigPath,
		"path to databases.json (default /etc/bugswatch/databases.json, or $BUGSWATCH_DB_CONFIG)")
	flag.Parse()

	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	sigCh := make(chan os.Signal, 1)
	signal.Notify(sigCh, syscall.SIGINT, syscall.SIGTERM)
	go func() {
		<-sigCh
		cancel()
	}()

	agent.Run(ctx, cfg)
}

// ── db sub-commands ──────────────────────────────────────────────────────────

func runDBCmd(args []string) {
	if len(args) == 0 {
		fmt.Fprintln(os.Stderr, "usage: bugswatch db <add|remove|list> [args]")
		os.Exit(1)
	}

	// Allow --db-config as the first flag of a db sub-command.
	cfgPath := config.DefaultDBConfigPath
	if v := os.Getenv("BUGSWATCH_DB_CONFIG"); v != "" {
		cfgPath = v
	}
	if len(args) >= 2 && args[0] == "--db-config" {
		cfgPath = args[1]
		args = args[2:]
	}

	switch args[0] {
	case "add":
		if len(args) < 3 {
			fmt.Fprintln(os.Stderr, "usage: bugswatch db add <driver> <url>")
			fmt.Fprintln(os.Stderr, "drivers: mysql, mariadb, postgres, redis, mongodb, sqlite")
			os.Exit(1)
		}
		dbAdd(cfgPath, args[1], args[2])

	case "remove":
		if len(args) < 2 {
			fmt.Fprintln(os.Stderr, "usage: bugswatch db remove <driver>")
			os.Exit(1)
		}
		dbRemove(cfgPath, args[1])

	case "list":
		dbList(cfgPath)

	default:
		fmt.Fprintf(os.Stderr, "unknown db command %q\n", args[0])
		os.Exit(1)
	}
}

func dbAdd(cfgPath, driver, url string) {
	entries, err := dbmanager.ReadEntries(cfgPath)
	if err != nil {
		log.Fatalf("read config: %v", err)
	}

	found := false
	for i, e := range entries {
		if e.Driver == driver {
			entries[i].URL = url
			found = true
			break
		}
	}
	if !found {
		entries = append(entries, dbmanager.Entry{Driver: driver, URL: url})
	}

	if err := dbmanager.WriteEntries(cfgPath, entries); err != nil {
		log.Fatalf("write config: %v", err)
	}
	fmt.Printf("added %s → %s\n", driver, cfgPath)
}

func dbRemove(cfgPath, driver string) {
	entries, err := dbmanager.ReadEntries(cfgPath)
	if err != nil {
		log.Fatalf("read config: %v", err)
	}

	next := entries[:0]
	for _, e := range entries {
		if e.Driver != driver {
			next = append(next, e)
		}
	}

	if err := dbmanager.WriteEntries(cfgPath, next); err != nil {
		log.Fatalf("write config: %v", err)
	}
	fmt.Printf("removed %s from %s\n", driver, cfgPath)
}

func dbList(cfgPath string) {
	entries, err := dbmanager.ReadEntries(cfgPath)
	if err != nil {
		log.Fatalf("read config: %v", err)
	}
	if len(entries) == 0 {
		fmt.Println("no database monitors configured")
		return
	}
	enc := json.NewEncoder(os.Stdout)
	enc.SetIndent("", "  ")
	enc.Encode(entries)
}