package browserbridge

import (
	"encoding/json"
	"errors"
	"fmt"
	"os"
	"os/exec"
	"path/filepath"
	"slices"
	"strings"
)

const browserExtensionName = "KeePassGO Browser"

type extensionManifestMetadata struct {
	Name string `json:"name"`
}

func ResolveBridgeBinaryPath(appBinaryPath string) (string, error) {
	path := strings.TrimSpace(appBinaryPath)
	if path == "" {
		var err error
		path, err = os.Executable()
		if err != nil {
			return "", fmt.Errorf("resolve app executable: %w", err)
		}
	}
	if strings.TrimSpace(path) == "" {
		return "", fmt.Errorf("app executable path is required")
	}
	if filepath.Base(path) == "keepassgo-browser-bridge" {
		return path, nil
	}
	candidate := filepath.Join(filepath.Dir(path), "keepassgo-browser-bridge")
	if info, err := os.Stat(candidate); err == nil && !info.IsDir() {
		return candidate, nil
	}
	resolved, err := exec.LookPath("keepassgo-browser-bridge")
	if err == nil {
		return resolved, nil
	}
	return "", fmt.Errorf("locate keepassgo-browser-bridge next to %q or in PATH: %w", path, err)
}

func EnsureNativeHostManifests(appBinaryPath string) error {
	bridgePath, err := ResolveBridgeBinaryPath(appBinaryPath)
	if err != nil {
		return err
	}
	var errs []error
	if _, err := InstallManifest(BrowserFirefox, bridgePath, "", ""); err != nil {
		errs = append(errs, fmt.Errorf("install firefox native host: %w", err))
	}
	for _, browser := range []Browser{BrowserChrome, BrowserChromium} {
		ids, err := DiscoverInstalledExtensionIDs(browser)
		if err != nil {
			errs = append(errs, fmt.Errorf("discover %s extension ids: %w", browser, err))
			continue
		}
		if len(ids) == 0 {
			continue
		}
		if _, err := InstallManifestSet(browser, bridgePath, ids, ""); err != nil {
			errs = append(errs, fmt.Errorf("install %s native host: %w", browser, err))
		}
	}
	return errors.Join(errs...)
}

func DiscoverInstalledExtensionIDs(browser Browser) ([]string, error) {
	root, err := defaultBrowserProfileRoot(browser)
	if err != nil {
		return nil, err
	}
	return DiscoverInstalledExtensionIDsInRoot(root)
}

func DiscoverInstalledExtensionIDsInRoot(root string) ([]string, error) {
	base := strings.TrimSpace(root)
	if base == "" {
		return nil, fmt.Errorf("browser profile root is required")
	}
	pattern := filepath.Join(base, "*", "Extensions", "*", "*", "manifest.json")
	paths, err := filepath.Glob(pattern)
	if err != nil {
		return nil, fmt.Errorf("glob browser extensions: %w", err)
	}
	ids := make(map[string]struct{}, len(paths))
	for _, path := range paths {
		ok, err := isKeePassGOExtensionManifest(path)
		if err != nil {
			return nil, err
		}
		if !ok {
			continue
		}
		id := filepath.Base(filepath.Dir(filepath.Dir(path)))
		if strings.TrimSpace(id) == "" {
			continue
		}
		ids[id] = struct{}{}
	}
	out := make([]string, 0, len(ids))
	for id := range ids {
		out = append(out, id)
	}
	slices.Sort(out)
	return out, nil
}

func InstallManifestSet(browser Browser, binaryPath string, extensionIDs []string, outputPath string) (string, error) {
	manifest, err := ManifestSet(browser, binaryPath, extensionIDs)
	if err != nil {
		return "", err
	}
	path := strings.TrimSpace(outputPath)
	if path == "" {
		path, err = DefaultManifestPath(browser)
		if err != nil {
			return "", err
		}
	}
	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
		return "", fmt.Errorf("create native host manifest dir: %w", err)
	}
	data, err := json.MarshalIndent(manifest, "", "  ")
	if err != nil {
		return "", fmt.Errorf("encode native host manifest: %w", err)
	}
	data = append(data, '\n')
	if err := os.WriteFile(path, data, 0o644); err != nil {
		return "", fmt.Errorf("write native host manifest: %w", err)
	}
	return path, nil
}

func ManifestSet(browser Browser, binaryPath string, extensionIDs []string) (NativeHostManifest, error) {
	path := strings.TrimSpace(binaryPath)
	if path == "" {
		return NativeHostManifest{}, fmt.Errorf("native host binary path is required")
	}
	switch browser {
	case BrowserFirefox:
		return Manifest(browser, path, "")
	case BrowserChrome, BrowserChromium:
		ids := normalizedExtensionIDs(extensionIDs)
		if len(ids) == 0 {
			return NativeHostManifest{}, fmt.Errorf("%s extension id is required", browser)
		}
		origins := make([]string, 0, len(ids))
		for _, id := range ids {
			origins = append(origins, "chrome-extension://"+id+"/")
		}
		return NativeHostManifest{
			Name:           NativeHostName,
			Description:    "KeePassGO browser bridge",
			Path:           path,
			Type:           "stdio",
			AllowedOrigins: origins,
		}, nil
	default:
		return NativeHostManifest{}, fmt.Errorf("unsupported browser %q", browser)
	}
}

func defaultBrowserProfileRoot(browser Browser) (string, error) {
	home, err := os.UserHomeDir()
	if err != nil {
		return "", err
	}
	switch browser {
	case BrowserChrome:
		return filepath.Join(home, ".config", "google-chrome"), nil
	case BrowserChromium:
		return filepath.Join(home, ".config", "chromium"), nil
	default:
		return "", fmt.Errorf("installed extension discovery is unsupported for %q", browser)
	}
}

func isKeePassGOExtensionManifest(path string) (bool, error) {
	data, err := os.ReadFile(path)
	if err != nil {
		return false, fmt.Errorf("read extension manifest %q: %w", path, err)
	}
	var metadata extensionManifestMetadata
	if err := json.Unmarshal(data, &metadata); err != nil {
		return false, fmt.Errorf("decode extension manifest %q: %w", path, err)
	}
	return strings.TrimSpace(metadata.Name) == browserExtensionName, nil
}

func normalizedExtensionIDs(ids []string) []string {
	seen := make(map[string]struct{}, len(ids))
	out := make([]string, 0, len(ids))
	for _, raw := range ids {
		id := strings.TrimSpace(raw)
		if id == "" {
			continue
		}
		if _, ok := seen[id]; ok {
			continue
		}
		seen[id] = struct{}{}
		out = append(out, id)
	}
	slices.Sort(out)
	return out
}