package lua

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

// newPluginVM builds a VM plus a plugin registry rooted at dir.
func newPluginVM(t *testing.T) (*VM, *Plugins, string) {
	t.Helper()
	dir := filepath.Join(t.TempDir(), "adapters")
	vm := NewVM(dir)
	if err := vm.Start(); err != nil {
		t.Fatalf("vm start: %v", err)
	}
	t.Cleanup(vm.Stop)
	pdir := filepath.Join(t.TempDir(), "plugins")
	return vm, NewPlugins(vm, pdir), pdir
}

// loadPlugin writes one plugin to disk and loads it.
func loadPlugin(t *testing.T, ps *Plugins, name, code string) error {
	t.Helper()
	if err := os.MkdirAll(ps.dir, 0755); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(filepath.Join(ps.dir, name+".lua"), []byte(code), 0644); err != nil {
		t.Fatal(err)
	}
	return ps.LoadSource(name, code)
}

// TestPluginManifestAndHooks: the two hook registration forms both work and the
// manifest is read.
func TestPluginManifestAndHooks(t *testing.T) {
	_, ps, _ := newPluginVM(t)
	code := `
local p = {}
p.name = "demo"
p.version = "1.2.3"
p.description = "a demo plugin"
p.author = "tester"
p.hooks = { request_end = "on_end" }
function p.on_end(payload)
  payload.seen = true
  payload.name_seen = "demo"
  return payload
end
return p
`
	if err := loadPlugin(t, ps, "demo", code); err != nil {
		t.Fatalf("load: %v", err)
	}
	list := ps.List()
	if len(list) != 1 {
		t.Fatalf("List() = %d plugins, want 1", len(list))
	}
	if list[0]["name"] != "demo" || list[0]["version"] != "1.2.3" {
		t.Errorf("manifest not read: %+v", list[0])
	}
	hooks := list[0]["hooks"].([]string)
	if len(hooks) != 1 || hooks[0] != string(StageRequestEnd) {
		t.Errorf("hooks = %v, want [request_end]", hooks)
	}
	out := ps.Fire(StageRequestEnd, map[string]interface{}{"model": "m"})
	if out["seen"] != true || out["name_seen"] != "demo" {
		t.Errorf("hook did not mutate payload: %+v", out)
	}
}

// TestPluginAnonymousHookForm: `request_end = function() end` directly on the
// table must register too, since a single-hook plugin should not need a name.
func TestPluginAnonymousHookForm(t *testing.T) {
	_, ps, _ := newPluginVM(t)
	code := `
local p = { name = "anon" }
p.request_end = function(payload)
  payload.hit = 1
  return payload
end
return p
`
	if err := loadPlugin(t, ps, "anon", code); err != nil {
		t.Fatalf("load: %v", err)
	}
	out := ps.Fire(StageRequestEnd, map[string]interface{}{})
	if out["hit"] != float64(1) {
		t.Errorf("anonymous hook did not fire: %+v", out)
	}
}

// TestPluginHookStagesFireInOrder: each stage reaches only its own hooks.
func TestPluginHookStagesFireInOrder(t *testing.T) {
	_, ps, _ := newPluginVM(t)
	code := `
local p = { name = "stages" }
p.hooks = {
  request_start = "s1",
  routed = "s2",
  request_end = "s3",
}
function p.s1(x) x.order = (x.order or "") .. "1" return x end
function p.s2(x) x.order = (x.order or "") .. "2" return x end
function p.s3(x) x.order = (x.order or "") .. "3" return x end
return p
`
	if err := loadPlugin(t, ps, "stages", code); err != nil {
		t.Fatalf("load: %v", err)
	}
	payload := map[string]interface{}{}
	ps.Fire(StageRequestStart, payload)
	ps.Fire(StageRouted, payload)
	ps.Fire(StageRequestEnd, payload)
	if payload["order"] != "123" {
		t.Errorf("stage order = %v, want \"123\"", payload["order"])
	}
}

// TestPluginErrorIsContained is the critical safety property: a throwing hook
// must not propagate. Forwarding depends on it.
func TestPluginErrorIsContained(t *testing.T) {
	_, ps, _ := newPluginVM(t)
	code := `
local p = { name = "boom" }
p.hooks = { request_end = "kaboom" }
function p.kaboom(payload)
  error("intentional plugin failure")
end
return p
`
	if err := loadPlugin(t, ps, "boom", code); err != nil {
		t.Fatalf("load: %v", err)
	}
	// Must not panic and must return the payload unchanged.
	out := ps.Fire(StageRequestEnd, map[string]interface{}{"model": "m"})
	if out["model"] != "m" {
		t.Errorf("payload was altered by a failing plugin: %+v", out)
	}
	// And the failure must be visible, not silent.
	errs := ps.HookErrors()
	if errs["request_end"] == nil {
		t.Error("a failing plugin left no error record; it would be silently missing")
	}
}

// TestPluginFailingHookDoesNotBlockLaterPlugins: one bad plugin must not stop
// the next one from running.
func TestPluginFailingHookDoesNotBlockLaterPlugins(t *testing.T) {
	_, ps, _ := newPluginVM(t)
	bad := `
local p = { name = "bad" }
p.hooks = { request_end = "f" }
function p.f(x) error("boom") end
return p
`
	good := `
local p = { name = "good" }
p.hooks = { request_end = "f" }
function p.f(x) x.good = true return x end
return p
`
	_ = loadPlugin(t, ps, "bad", bad)
	if err := loadPlugin(t, ps, "good", good); err != nil {
		t.Fatalf("load good: %v", err)
	}
	out := ps.Fire(StageRequestEnd, map[string]interface{}{})
	if out["good"] != true {
		t.Errorf("a good plugin was blocked by a failing one: %+v", out)
	}
}

// TestPluginSyntaxErrorIsIsolated: a plugin that will not compile is listed
// with its error and is never called — it must not prevent LoadDir from loading
// the rest.
func TestPluginSyntaxErrorIsIsolated(t *testing.T) {
	_, ps, _ := newPluginVM(t)
	broken := "this is not lua((("
	good := `
local p = { name = "ok" }
p.hooks = { request_end = "f" }
function p.f(x) x.ok = true return x end
return p
`
	_ = loadPlugin(t, ps, "broken", broken)
	if err := loadPlugin(t, ps, "ok", good); err != nil {
		t.Fatalf("load ok: %v", err)
	}
	if err := ps.LoadDir(); err != nil {
		t.Fatalf("LoadDir: %v", err)
	}
	// The broken plugin must not be callable and must carry an error.
	for _, row := range ps.List() {
		if row["name"] == "broken" {
			if row["loaded"] == true {
				t.Error("a plugin with a syntax error reported itself as loaded")
			}
			if row["error"] == nil || row["error"] == "" {
				t.Error("a broken plugin carries no error message")
			}
		}
	}
	// The good plugin still works.
	out := ps.Fire(StageRequestEnd, map[string]interface{}{})
	if out["ok"] != true {
		t.Errorf("good plugin stopped working: %+v", out)
	}
}

// TestPluginUIExtension: a plugin can contribute a page and elements.
func TestPluginUIExtension(t *testing.T) {
	_, ps, _ := newPluginVM(t)
	code := `
local p = { name = "ui" }
p.hooks = { request_end = "f" }
function p.f(x) return x end
p.ui = {
  page = {
    page_id = "billing",
    title = "Billing",
    icon = "💰",
    order = 50,
    mount = "<div id=billing>hi</div><script>console.log('m')</script>",
  },
  elements = {
    { target = "status", anchor = "top", mount = "<div>cost</div>" },
  },
}
return p
`
	if err := loadPlugin(t, ps, "ui", code); err != nil {
		t.Fatalf("load: %v", err)
	}
	ui := ps.UI()
	if ui.Page == nil {
		t.Fatal("no page contributed")
	}
	if ui.Page.PageID != "billing" || ui.Page.Title != "Billing" {
		t.Errorf("page = %+v", ui.Page)
	}
	if !strings.Contains(ui.Page.Mount, "console.log") {
		t.Error("mount lost its script content")
	}
	if len(ui.Elements) != 1 || ui.Elements[0].Target != "status" {
		t.Errorf("elements = %+v", ui.Elements)
	}
}

// TestPluginHookReturnsNilIsNoOpinion: a hook returning nothing must leave the
// payload untouched (plugins should not be forced to echo it back).
func TestPluginHookReturnsNilIsNoOpinion(t *testing.T) {
	_, ps, _ := newPluginVM(t)
	code := `
local p = { name = "silent" }
p.hooks = { request_end = "f" }
function p.f(payload)
  -- records nothing, returns nothing
  return nil
end
return p
`
	if err := loadPlugin(t, ps, "silent", code); err != nil {
		t.Fatalf("load: %v", err)
	}
	out := ps.Fire(StageRequestEnd, map[string]interface{}{"model": "m", "ok": true})
	if out["model"] != "m" || out["ok"] != true {
		t.Errorf("a no-op hook disturbed the payload: %+v", out)
	}
}

// TestPluginUIJSONShape is a wire-format guard: the kernel sends this to the
// browser, so the shape is a contract with the WebUI.
func TestPluginUIJSONShape(t *testing.T) {
	_, ps, _ := newPluginVM(t)
	code := `
local p = { name = "shape" }
p.hooks = { request_end = "f" }
function p.f(x) return x end
p.ui = { elements = { { target = "keys", mount = "<b>k</b>" } } }
return p
`
	if err := loadPlugin(t, ps, "shape", code); err != nil {
		t.Fatalf("load: %v", err)
	}
	b, err := json.Marshal(ps.UI())
	if err != nil {
		t.Fatalf("marshal UI: %v", err)
	}
	var view struct {
		Elements []struct {
			Target string `json:"target"`
			Mount  string `json:"mount"`
		} `json:"elements"`
	}
	if err := json.Unmarshal(b, &view); err != nil {
		t.Fatalf("unmarshal: %v", err)
	}
	if len(view.Elements) != 1 || view.Elements[0].Target != "keys" {
		t.Errorf("UI JSON shape = %+v", view.Elements)
	}
}

// TestPluginFireWithNoPluginsIsNoop: an empty registry must not allocate or fail.
func TestPluginFireWithNoPluginsIsNoop(t *testing.T) {
	_, ps, _ := newPluginVM(t)
	in := map[string]interface{}{"a": 1}
	out := ps.Fire(StageRequestEnd, in)
	if out["a"] != 1 || ps.Count() != 0 {
		t.Errorf("empty registry misbehaved: %+v", out)
	}
}