package plugin

import (
	"encoding/json"
	"os"
	"path/filepath"
	"strings"
)

// Middleware is the gateway middleware a plugin at target has: the file
// its package.json's magpie.middleware names, or the file itself for a
// path to a *.middleware.js (or .mjs). only is whether it is nothing
// else: no OpenCode plugin for the host to load (no main, no exports).
func Middleware(target string) (file string, only bool) {
	st, err := os.Stat(target)
	if err != nil {
		return "", false
	}
	if !st.IsDir() {
		base := strings.ToLower(filepath.Base(target))
		if strings.HasSuffix(base, ".middleware.js") || strings.HasSuffix(base, ".middleware.mjs") {
			return target, true
		}
		return "", false
	}
	b, err := os.ReadFile(filepath.Join(target, "package.json"))
	if err != nil {
		return "", false
	}
	var pkg struct {
		Main    string          `json:"main"`
		Exports json.RawMessage `json:"exports"`
		Magpie  struct {
			Middleware string `json:"middleware"`
		} `json:"magpie"`
	}
	if json.Unmarshal(b, &pkg) != nil || strings.TrimSpace(pkg.Magpie.Middleware) == "" {
		return "", false
	}
	file = filepath.Join(target, filepath.FromSlash(strings.TrimSpace(pkg.Magpie.Middleware)))
	return file, pkg.Main == "" && len(pkg.Exports) == 0
}

// ListStamp changes when plugins.json does.
func ListStamp() string { return listStamp() }

// OptionsExample is the options a plugin at target suggests, from its
// package.json's magpie.options: what its options editor starts from
// before any are set.
func OptionsExample(target string) map[string]any {
	b, err := os.ReadFile(filepath.Join(target, "package.json"))
	if err != nil {
		return nil
	}
	var pkg struct {
		Magpie struct {
			Options map[string]any `json:"options"`
		} `json:"magpie"`
	}
	if json.Unmarshal(b, &pkg) != nil {
		return nil
	}
	return pkg.Magpie.Options
}