package client

import (
	"bufio"
	"encoding/json"
	"errors"
	"fmt"
	"os"
	"path/filepath"
	"strconv"
	"strings"
)

// ImportOptions describes importing an official opentunnel CLI profile.
type ImportOptions struct {
	Profile    string
	API        string
	ConfigPath string
	Force      bool
}

// ImportResult summarizes a successful import.
type ImportResult struct {
	TunnelID   string
	Hostname   string
	Routes     []string
	ConfigPath string
	Source     string
}

type officialTunnel struct {
	ID                string `json:"id"`
	Hostname          string `json:"hostname"`
	CertificateExpiry string `json:"certificateExpiry"`
}

// Import copies the identity and routes of the official Rust CLI into this
// client's JSON config. The tunnel ID, token, private key and certificate are
// preserved, so the server sees the same tunnel.
func Import(opts ImportOptions) (ImportResult, error) {
	if opts.Profile == "" {
		opts.Profile = "default"
	}
	if !routeNameRE.MatchString(opts.Profile) {
		return ImportResult{}, fmt.Errorf("invalid profile name %q", opts.Profile)
	}
	if opts.API == "" {
		return ImportResult{}, errors.New("--api is required")
	}
	api, err := NormalizeAPI(opts.API)
	if err != nil {
		return ImportResult{}, err
	}
	if opts.ConfigPath == "" {
		opts.ConfigPath = DefaultPath()
	}
	if _, err := os.Stat(opts.ConfigPath); err == nil && !opts.Force {
		return ImportResult{}, fmt.Errorf("%s already exists; use --force to overwrite", opts.ConfigPath)
	}

	dataDir := xdgDir("XDG_DATA_HOME", ".local/share", "opentunnel", opts.Profile)
	configDir := xdgDir("XDG_CONFIG_HOME", ".config", "opentunnel")
	routesPath := filepath.Join(configDir, opts.Profile+".toml")

	rawTunnel, err := os.ReadFile(filepath.Join(dataDir, "tunnel.json"))
	if err != nil {
		return ImportResult{}, fmt.Errorf("official tunnel.json: %w", err)
	}
	var official officialTunnel
	if err := json.Unmarshal(rawTunnel, &official); err != nil {
		return ImportResult{}, fmt.Errorf("official tunnel.json: %w", err)
	}
	if official.ID == "" || official.Hostname == "" {
		return ImportResult{}, errors.New("official tunnel.json has no id/hostname")
	}
	token, err := os.ReadFile(filepath.Join(dataDir, "token"))
	if err != nil {
		return ImportResult{}, fmt.Errorf("official token: %w", err)
	}
	keyPEM, err := os.ReadFile(filepath.Join(dataDir, "private-key.pem"))
	if err != nil {
		return ImportResult{}, fmt.Errorf("official private key: %w", err)
	}
	if _, err := parseKey(keyPEM); err != nil {
		return ImportResult{}, fmt.Errorf("official private key: %w", err)
	}
	certPEM, err := os.ReadFile(filepath.Join(dataDir, "certificate.pem"))
	if err != nil {
		return ImportResult{}, fmt.Errorf("official certificate: %w", err)
	}
	chainPEM, err := os.ReadFile(filepath.Join(dataDir, "chain.pem"))
	if err != nil && !errors.Is(err, os.ErrNotExist) {
		return ImportResult{}, fmt.Errorf("official chain: %w", err)
	}

	paths := ConfigPaths(opts.ConfigPath)
	if err := os.MkdirAll(paths.Dir, 0o700); err != nil {
		return ImportResult{}, err
	}
	if err := writeAtomic(paths.Key, keyPEM, 0o600); err != nil {
		return ImportResult{}, err
	}
	if err := writeAtomic(paths.Cert, certPEM, 0o644); err != nil {
		return ImportResult{}, err
	}
	if err := writeAtomic(paths.Chain, chainPEM, 0o644); err != nil {
		return ImportResult{}, err
	}
	if _, _, err := EnsureIdentity(paths, official.Hostname); err != nil {
		return ImportResult{}, fmt.Errorf("local CSR: %w", err)
	}

	cfg := &Config{
		API:               api,
		TunnelID:          official.ID,
		Hostname:          official.Hostname,
		Token:             strings.TrimSpace(string(token)),
		CertificateExpiry: official.CertificateExpiry,
		Routes:            map[string]Route{},
	}
	routes, err := readOfficialRoutes(routesPath)
	if err != nil {
		return ImportResult{}, err
	}
	for name, route := range routes {
		if err := cfg.AddRoute(name, route.Target, route.ProxyProtocol); err != nil {
			return ImportResult{}, err
		}
	}
	if cfg.Token == "" {
		return ImportResult{}, errors.New("official token file is empty")
	}
	if err := cfg.Save(opts.ConfigPath); err != nil {
		return ImportResult{}, err
	}
	names := make([]string, 0, len(cfg.Routes))
	for name := range cfg.Routes {
		names = append(names, name)
	}
	return ImportResult{
		TunnelID:   cfg.TunnelID,
		Hostname:   cfg.Hostname,
		Routes:     names,
		ConfigPath: opts.ConfigPath,
		Source:     dataDir,
	}, nil
}

func xdgDir(env, fallback string, parts ...string) string {
	base := os.Getenv(env)
	if base == "" {
		home, err := os.UserHomeDir()
		if err != nil {
			base = "."
		} else {
			base = filepath.Join(home, fallback)
		}
	}
	return filepath.Join(append([]string{base}, parts...)...)
}

// readOfficialRoutes parses the subset of TOML the official CLI writes:
//
//	[routes]
//	web = "127.0.0.1:3000"
//	api = { target = "127.0.0.1:4000", proxy_protocol = "v2" }
func readOfficialRoutes(path string) (map[string]Route, error) {
	out := map[string]Route{}
	file, err := os.Open(path)
	if errors.Is(err, os.ErrNotExist) {
		return out, nil
	}
	if err != nil {
		return nil, err
	}
	defer file.Close()

	inRoutes := false
	scanner := bufio.NewScanner(file)
	for scanner.Scan() {
		line := strings.TrimSpace(scanner.Text())
		if line == "" || strings.HasPrefix(line, "#") {
			continue
		}
		if strings.HasPrefix(line, "[") && strings.HasSuffix(line, "]") {
			inRoutes = line == "[routes]"
			continue
		}
		if !inRoutes {
			continue
		}
		name, value, ok := strings.Cut(line, "=")
		if !ok {
			return nil, fmt.Errorf("%s: bad route line %q", path, line)
		}
		name = strings.TrimSpace(name)
		if unquoted, err := strconv.Unquote(name); err == nil {
			name = unquoted
		}
		value = strings.TrimSpace(value)
		route, err := parseRouteValue(value)
		if err != nil {
			return nil, fmt.Errorf("%s: route %s: %w", path, name, err)
		}
		out[name] = route
	}
	if err := scanner.Err(); err != nil {
		return nil, err
	}
	return out, nil
}

func parseRouteValue(value string) (Route, error) {
	if strings.HasPrefix(value, "\"") {
		target, err := strconv.Unquote(value)
		if err != nil {
			return Route{}, err
		}
		return Route{Target: target}, nil
	}
	if strings.HasPrefix(value, "{") && strings.HasSuffix(value, "}") {
		route := Route{}
		body := strings.TrimSpace(value[1 : len(value)-1])
		for _, field := range strings.Split(body, ",") {
			key, val, ok := strings.Cut(strings.TrimSpace(field), "=")
			if !ok {
				continue
			}
			key = strings.TrimSpace(key)
			val = strings.TrimSpace(val)
			unquoted, err := strconv.Unquote(val)
			if err != nil {
				return Route{}, err
			}
			switch key {
			case "target":
				route.Target = unquoted
			case "proxy_protocol":
				route.ProxyProtocol = unquoted
			}
		}
		if route.Target == "" {
			return Route{}, errors.New("inline route has no target")
		}
		return route, nil
	}
	return Route{}, fmt.Errorf("unsupported route value %q", value)
}