// Copyright 2024 Matthew Rich <matthewrich.conf@gmail.com>. All rights reserved.

package resource

import (
_	"errors"
	"context"
	"encoding/json"
	"fmt"
	"io"
	"gopkg.in/yaml.v3"
	"log/slog"
_	"gitea.rosskeen.house/rosskeen.house/machine"
	"gitea.rosskeen.house/pylon/luaruntime"
	"decl/internal/codec"
	"decl/internal/config"
)

type ConfigName string

type DeclarationType struct {
	Type TypeName `json:"type" yaml:"type"`
	Transition string `json:"transition,omitempty" yaml:"transition,omitempty"`
	Config ConfigName `json:"config,omitempty" yaml:"config,omitempty"`
}

type Declaration struct {
	Type TypeName `json:"type" yaml:"type"`
	Transition string `json:"transition,omitempty" yaml:"transition,omitempty"`
	Attributes Resource `json:"attributes" yaml:"attributes"`
	Config ConfigName `json:"config,omitempty" yaml:"config,omitempty"`
	runtime luaruntime.LuaRunner
	document *Document
	configBlock *config.Block
}

type ResourceLoader interface {
	LoadDecl(string) error
}

type StateTransformer interface {
	Apply() error
}

func NewDeclaration() *Declaration {
	return &Declaration{}
}

func NewDeclarationFromDocument(document *Document) *Declaration {
	return &Declaration{ document: document }
}

func (d *Declaration) SetDocument(newDocument *Document) {
	slog.Info("Declaration.SetDocument()")
	d.document = newDocument
	d.SetConfig(d.document.config)
	d.Attributes.SetResourceMapper(d.document.uris)
}

func (d *Declaration) ResolveId(ctx context.Context) string {
	defer func() {
		if r := recover(); r != nil {
			slog.Info("Declaration.ResolveId() - panic", "recover", r, "state", d.Attributes.StateMachine())
			if triggerErr := d.Attributes.StateMachine().Trigger("notexists"); triggerErr != nil {
				panic(triggerErr)
			}
		}
	}()
	slog.Info("Declaration.ResolveId()")
	id := d.Attributes.ResolveId(ctx)
	return id
}

func (d *Declaration) Clone() *Declaration {
	return &Declaration {
		Type: d.Type,
    Transition: d.Transition,
		Attributes: d.Attributes.Clone(),
		runtime: luaruntime.New(),
		Config: d.Config,
	}
}

func (d *Declaration) Load(r io.Reader) error {
	return codec.NewYAMLDecoder(r).Decode(d)
}

func (d *Declaration) LoadDecl(yamlResourceDeclaration string) error {
	return codec.NewYAMLStringDecoder(yamlResourceDeclaration).Decode(d)
}

func (d *Declaration) NewResource() error {
	uri := fmt.Sprintf("%s://", d.Type)
	newResource, err := ResourceTypes.New(uri)
	d.Attributes = newResource
	return err
}

func (d *Declaration) Resource() Resource {
	return d.Attributes
}

func (d *Declaration) Apply() (result error) {
	defer func() {
		if r := recover(); r != nil {
			result = fmt.Errorf("%s", r)
		}
	}()

	stater := d.Attributes.StateMachine()
	slog.Info("Declaration.Apply()", "machine", stater, "machine.state", stater.CurrentState(), "uri", d.Attributes.URI())
	switch d.Transition {
	case "read":
		result = stater.Trigger("read")
	case "delete", "absent":
		if stater.CurrentState() == "present" {
			result = stater.Trigger("delete")
		}
	case "update":
		if result = stater.Trigger("update"); result != nil {
			return result
		}
		result = stater.Trigger("read")
	default:
		fallthrough
	case "create", "present":
		if stater.CurrentState() == "absent" || stater.CurrentState() == "unknown" {
			if result = stater.Trigger("create"); result != nil {
				return result
			}
		}
		result = stater.Trigger("read")
	}
	return result
}

func (d *Declaration) SetConfig(configDoc *config.Document) {
	if configDoc != nil {
		if configDoc.Has(string(d.Config)) {
			d.configBlock = configDoc.Get(string(d.Config))
			d.Attributes.UseConfig(d.configBlock)
		}
	}
}

func (d *Declaration) SetURI(uri string) error {
	slog.Info("Declaration.SetURI()", "uri", uri, "declaration", d)
	d.Attributes = NewResource(uri)
	if d.Attributes == nil {
		return ErrUnknownResourceType
	}
	d.Type = TypeName(d.Attributes.Type())
	_,e := d.Attributes.Read(context.Background()) // fix context
	return e
}


func (d *Declaration) UnmarshalValue(value *DeclarationType) error {
	d.Type = value.Type
	d.Transition = value.Transition
	d.Config = value.Config
	newResource, resourceErr := ResourceTypes.New(fmt.Sprintf("%s://", value.Type))
	if resourceErr != nil {
		slog.Info("Declaration.UnmarshalValue", "value", value, "error", resourceErr)
		return resourceErr
	}
	d.Attributes = newResource
	return nil
}

func (d *Declaration) UnmarshalYAML(value *yaml.Node) error {
	t := &DeclarationType{}
	if unmarshalResourceTypeErr := value.Decode(t); unmarshalResourceTypeErr != nil {
		return unmarshalResourceTypeErr
	}

	if err := d.UnmarshalValue(t); err != nil {
		return err
	}

	resourceAttrs := struct {
		Attributes yaml.Node `json:"attributes"`
	}{}
	if unmarshalAttributesErr := value.Decode(&resourceAttrs); unmarshalAttributesErr != nil {
		return unmarshalAttributesErr
	}
	if unmarshalResourceErr := resourceAttrs.Attributes.Decode(d.Attributes); unmarshalResourceErr != nil {
		return unmarshalResourceErr
	}
	return nil
}

func (d *Declaration) UnmarshalJSON(data []byte) error {
	t := &DeclarationType{}
	if unmarshalResourceTypeErr := json.Unmarshal(data, t); unmarshalResourceTypeErr != nil {
		return unmarshalResourceTypeErr
	}

	if err := d.UnmarshalValue(t); err != nil {
		return err
	}

	resourceAttrs := struct {
		Attributes Resource `json:"attributes"`
	}{Attributes: d.Attributes}
	if unmarshalAttributesErr := json.Unmarshal(data, &resourceAttrs); unmarshalAttributesErr != nil {
		return unmarshalAttributesErr
	}

	return nil
}

/*
func (d *Declaration) MarshalJSON() ([]byte, error) {
  buf := new(bytes.Buffer)
  buf.WriteByte('"')
  buf.WriteString("value"))
  buf.WriteByte('"')
  return buf.Bytes(), nil
}
*/

func (d *Declaration) MarshalYAML() (any, error) {
	return d, nil
}

/*
func (l *LuaWorker) Receive(m message.Envelope) {
  s := m.Sender()
  switch b := m.Body().(type) {
  case *message.Error:
  //  case *worker.Terminated:
  case *CodeExecute:
    stackSize := l.runtime.Api().GetTop()
    if e := l.runtime.LoadScriptFromString(b.Code); e != nil {
      s.Send(message.New(&message.Error{ E: e }, l))
    }
    returnsCount := l.runtime.Api().GetTop() - stackSize
    if len(b.Entrypoint) == 0 {
      if ! l.runtime.Api().IsNil(-1) {
        if returnsCount == 0 {
            s.Send(message.New(&CodeResult{ Result: []interface{}{ 0 } }, l))
        } else {
          lr,le := l.runtime.CopyReturnValuesFromCall(int(returnsCount))
          if le != nil {
            s.Send(message.New(&message.Error{ E: le }, l))
          } else {
            s.Send(message.New(&CodeResult{ Result: lr }, l))
          }
        }
      }
    } else {
      r,ce := l.runtime.CallFunction(b.Entrypoint, b.Args)
      if ce != nil {
        s.Send(message.New(&message.Error{ E: ce }, l))
      }
      s.Send(message.New(&CodeResult{ Result: r }, l))
    }
  }
}
*/