package main

import (
	"context"
	"flag"
	"fmt"
	"os"
	"os/signal"
	"sort"
	"syscall"
	"time"
)

// version is overridden at build time via -ldflags '-X main.version=...'.
var version = "dev"

const usage = `rb-search — peek into a RabbitMQ queue without consuming.

Reads N=queue-depth messages with basic.get + manual ack, runs a substring
search in memory, prints matches, then requeues everything in reverse order
so the queue is restored byte-for-byte. Properties and headers are preserved
because messages are never republished.

Usage:
  rb-search [flags]                       # scan default server's queue
  rb-search --server prod --queue q       # scan a specific server
  rb-search list                          # list configured servers
  rb-search set-default <name>            # mark a server as default
  rb-search init                          # write a sample config

Config:
  Loaded from --config or $RB_SEARCH_CONFIG or
  $XDG_CONFIG_HOME/rb-search/config.json (default ~/.config/rb-search/config.json).

  If no config file exists, rb-search falls back to env vars:
    EVENTBUS_AMQP_HOST  (required to enable the fallback)
    EVENTBUS_AMQP_USER, EVENTBUS_AMQP_PASS
    EVENTBUS_AMQP_PORT  (default 5672)
    EVENTBUS_AMQP_VHOST (default /)
  These materialize a synthetic server named "env" that becomes the default.

Flags:
  --config PATH      Config file path.
  --server NAME      Server alias (overrides 'default').
  --queue NAME       Queue to scan. Required for the scan command.
  --search TEXT      Substring to match against message body. Empty -> print all.
  --full             Include envelope (exchange, routing-key, headers, props).
                     Default prints only the body, pretty-printed if it is JSON.
  --max-body N       Truncate body to N bytes when printing (0 = full). Default 0.
  --timeout DUR      AMQP dial timeout. Default 30s.
  --json             Machine-readable output. Combine with --full to emit a
                     full envelope object per message; without --full, emits
                     one body per line (compact JSON if the body is JSON,
                     otherwise the body as a JSON string).

Exit status:
  0  success (any number of matches)
  1  runtime error
  2  bad usage
`

func main() {
	if err := run(os.Args[1:]); err != nil {
		fmt.Fprintln(os.Stderr, "error:", err)
		os.Exit(1)
	}
}

func run(args []string) error {
	if len(args) > 0 {
		switch args[0] {
		case "list", "ls":
			return cmdList(args[1:])
		case "set-default":
			return cmdSetDefault(args[1:])
		case "init":
			return cmdInit(args[1:])
		case "version", "--version", "-V":
			fmt.Println(version)
			return nil
		case "help", "-h", "--help":
			fmt.Print(usage)
			return nil
		}
	}
	return cmdScan(args)
}

func newFlagSet(name string) *flag.FlagSet {
	fs := flag.NewFlagSet(name, flag.ContinueOnError)
	fs.SetOutput(os.Stderr)
	fs.Usage = func() {
		fmt.Fprint(os.Stderr, usage)
	}
	return fs
}

func cmdScan(args []string) error {
	fs := newFlagSet("scan")
	configPath := fs.String("config", "", "config file path")
	server := fs.String("server", "", "server alias")
	queue := fs.String("queue", "", "queue name")
	search := fs.String("search", "", "substring to match in body")
	maxBody := fs.Int("max-body", 0, "truncate body to N bytes (0 = full)")
	timeout := fs.Duration("timeout", 30*time.Second, "dial timeout")
	jsonOut := fs.Bool("json", false, "machine-readable JSON output (body only; combine with --full for envelope)")
	full := fs.Bool("full", false, "print full envelope (exchange, headers, props) instead of body only")
	if err := fs.Parse(args); err != nil {
		return err
	}
	if *queue == "" {
		fs.Usage()
		return fmt.Errorf("--queue is required")
	}

	cfg, err := loadConfig(*configPath)
	if err != nil {
		return err
	}
	name, srv, err := cfg.resolveServer(*server)
	if err != nil {
		return err
	}
	origin := "config"
	if cfg.fromEnv {
		origin = "env"
	}
	fmt.Fprintf(os.Stderr, "[rb-search] server=%s (%s) queue=%s search=%q\n", name, origin, *queue, *search)

	ctx, cancel := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
	defer cancel()

	return scanQueue(ctx, srv.URL, scanOptions{
		queue:   *queue,
		search:  *search,
		maxBody: *maxBody,
		timeout: *timeout,
		out:     os.Stdout,
		diag:    os.Stderr,
		jsonOut: *jsonOut,
		full:    *full,
	})
}

func cmdList(args []string) error {
	fs := newFlagSet("list")
	configPath := fs.String("config", "", "config file path")
	if err := fs.Parse(args); err != nil {
		return err
	}
	cfg, err := loadConfig(*configPath)
	if err != nil {
		return err
	}
	names := make([]string, 0, len(cfg.Servers))
	for n := range cfg.Servers {
		names = append(names, n)
	}
	sort.Strings(names)
	for _, n := range names {
		marker := " "
		if n == cfg.Default {
			marker = "*"
		}
		fmt.Printf("%s %-15s  %s\n", marker, n, cfg.Servers[n].URL)
	}
	if len(names) == 0 {
		fmt.Println("(no servers configured)")
	}
	if cfg.fromEnv {
		fmt.Fprintln(os.Stderr, "(synthetic config from EVENTBUS_AMQP_* env vars; run `rb-search init` to persist)")
	}
	return nil
}

func cmdSetDefault(args []string) error {
	fs := newFlagSet("set-default")
	configPath := fs.String("config", "", "config file path")
	if err := fs.Parse(args); err != nil {
		return err
	}
	if fs.NArg() != 1 {
		return fmt.Errorf("usage: rb-search set-default <server-name>")
	}
	name := fs.Arg(0)
	cfg, err := loadConfig(*configPath)
	if err != nil {
		return err
	}
	if _, ok := cfg.Servers[name]; !ok {
		return fmt.Errorf("unknown server %q", name)
	}
	cfg.Default = name
	if err := cfg.save(); err != nil {
		return err
	}
	fmt.Printf("default set to %q in %s\n", name, cfg.path)
	return nil
}

func cmdInit(args []string) error {
	fs := newFlagSet("init")
	configPath := fs.String("config", "", "config file path")
	if err := fs.Parse(args); err != nil {
		return err
	}
	path := *configPath
	if path == "" {
		path = defaultConfigPath()
	}
	if err := writeSampleConfig(path); err != nil {
		return err
	}
	fmt.Printf("wrote sample config to %s\n", path)
	return nil
}