package api

import (
	"encoding/json"
	"errors"
	"net/http"
	"regexp"
	"strings"
	"time"

	"codeberg.org/SquidSE/ClusterCanvas/service/internal/auth"
	"codeberg.org/SquidSE/ClusterCanvas/service/internal/settings"
)

type actionsResponse struct {
	Actions []settings.Action `json:"actions"`
}

type createActionRequest struct {
	Name        string                  `json:"name"`
	Description string                  `json:"description"`
	Kind        settings.ActionKind     `json:"kind"`
	Body        string                  `json:"body"`
	Env         []settings.ActionEnvVar `json:"env"`
}

type patchActionRequest struct {
	Name        *string                  `json:"name"`
	Description *string                  `json:"description"`
	Body        *string                  `json:"body"`
	Env         *[]settings.ActionEnvVar `json:"env"`
}

var envVarNamePattern = regexp.MustCompile(`^[A-Za-z_][A-Za-z0-9_]*$`)

var (
	errActionNameRequired = errors.New("action name is required")
	errActionBodyRequired = errors.New("action body is required")
	errActionKindInvalid  = errors.New("action kind must be shell or script")
	errActionNotFound     = errors.New("action not found")
	errActionBuiltinRO    = errors.New("built-in actions cannot be modified")
	errActionIDRequired   = errors.New("action id is required")
)

func actionsGetHandler(configDir string) http.HandlerFunc {
	return func(writer http.ResponseWriter, request *http.Request) {
		store, err := settings.LoadActionsOrSeed(configDir)
		if err != nil {
			writeJSON(writer, http.StatusInternalServerError, apiErrorResponse{Error: err.Error()})
			return
		}
		writeJSON(writer, http.StatusOK, actionsResponse{Actions: store.Actions})
	}
}

func actionsCreateHandler(configDir string) http.HandlerFunc {
	return func(writer http.ResponseWriter, request *http.Request) {
		if err := authorizeActionsCreate(request, configDir); err != nil {
			writeJSON(writer, http.StatusForbidden, apiErrorResponse{Error: err.Error()})
			return
		}

		var payload createActionRequest
		if err := json.NewDecoder(request.Body).Decode(&payload); err != nil {
			writeJSON(writer, http.StatusBadRequest, apiErrorResponse{Error: "invalid JSON body"})
			return
		}

		action, err := buildCustomAction(payload)
		if err != nil {
			writeJSON(writer, http.StatusBadRequest, apiErrorResponse{Error: err.Error()})
			return
		}

		store, err := settings.LoadActionsOrSeed(configDir)
		if err != nil {
			writeJSON(writer, http.StatusInternalServerError, apiErrorResponse{Error: err.Error()})
			return
		}

		store.Actions = append(store.Actions, action)
		if err := settings.SaveActions(configDir, store); err != nil {
			writeJSON(writer, http.StatusInternalServerError, apiErrorResponse{Error: err.Error()})
			return
		}

		writeJSON(writer, http.StatusOK, actionsResponse{Actions: store.Actions})
	}
}

func actionsPatchHandler(configDir string) http.HandlerFunc {
	return func(writer http.ResponseWriter, request *http.Request) {
		if err := authorizeActionsUpdate(request, configDir); err != nil {
			writeJSON(writer, http.StatusForbidden, apiErrorResponse{Error: err.Error()})
			return
		}

		actionID := strings.TrimSpace(request.URL.Query().Get("id"))
		if actionID == "" {
			writeJSON(writer, http.StatusBadRequest, apiErrorResponse{Error: errActionIDRequired.Error()})
			return
		}

		var payload patchActionRequest
		if err := json.NewDecoder(request.Body).Decode(&payload); err != nil {
			writeJSON(writer, http.StatusBadRequest, apiErrorResponse{Error: "invalid JSON body"})
			return
		}

		store, err := settings.LoadActionsOrSeed(configDir)
		if err != nil {
			writeJSON(writer, http.StatusInternalServerError, apiErrorResponse{Error: err.Error()})
			return
		}

		index := findActionIndex(store.Actions, actionID)
		if index < 0 {
			writeJSON(writer, http.StatusNotFound, apiErrorResponse{Error: errActionNotFound.Error()})
			return
		}
		if store.Actions[index].Builtin {
			writeJSON(writer, http.StatusBadRequest, apiErrorResponse{Error: errActionBuiltinRO.Error()})
			return
		}

		updated := store.Actions[index]
		if payload.Name != nil {
			updated.Name = strings.TrimSpace(*payload.Name)
		}
		if payload.Description != nil {
			updated.Description = strings.TrimSpace(*payload.Description)
		}
		if payload.Body != nil {
			updated.Body = strings.TrimSpace(*payload.Body)
		}
		if payload.Env != nil {
			updated.Env = *payload.Env
		}
		updated.UpdatedAt = time.Now().UTC()

		if err := validateActionFields(updated.Name, updated.Kind, updated.Body, updated.Env); err != nil {
			writeJSON(writer, http.StatusBadRequest, apiErrorResponse{Error: err.Error()})
			return
		}
		if updated.Env == nil {
			updated.Env = []settings.ActionEnvVar{}
		}

		store.Actions[index] = updated
		if err := settings.SaveActions(configDir, store); err != nil {
			writeJSON(writer, http.StatusInternalServerError, apiErrorResponse{Error: err.Error()})
			return
		}

		writeJSON(writer, http.StatusOK, actionsResponse{Actions: store.Actions})
	}
}

func actionsDeleteHandler(configDir string) http.HandlerFunc {
	return func(writer http.ResponseWriter, request *http.Request) {
		if err := authorizeActionsDelete(request, configDir); err != nil {
			writeJSON(writer, http.StatusForbidden, apiErrorResponse{Error: err.Error()})
			return
		}

		actionID := strings.TrimSpace(request.URL.Query().Get("id"))
		if actionID == "" {
			writeJSON(writer, http.StatusBadRequest, apiErrorResponse{Error: errActionIDRequired.Error()})
			return
		}

		store, err := settings.LoadActionsOrSeed(configDir)
		if err != nil {
			writeJSON(writer, http.StatusInternalServerError, apiErrorResponse{Error: err.Error()})
			return
		}

		index := findActionIndex(store.Actions, actionID)
		if index < 0 {
			writeJSON(writer, http.StatusNotFound, apiErrorResponse{Error: errActionNotFound.Error()})
			return
		}
		if store.Actions[index].Builtin {
			writeJSON(writer, http.StatusBadRequest, apiErrorResponse{Error: errActionBuiltinRO.Error()})
			return
		}

		store.Actions = append(store.Actions[:index], store.Actions[index+1:]...)
		if err := settings.SaveActions(configDir, store); err != nil {
			writeJSON(writer, http.StatusInternalServerError, apiErrorResponse{Error: err.Error()})
			return
		}

		writeJSON(writer, http.StatusOK, actionsResponse{Actions: store.Actions})
	}
}

func buildCustomAction(payload createActionRequest) (settings.Action, error) {
	name := strings.TrimSpace(payload.Name)
	description := strings.TrimSpace(payload.Description)
	body := strings.TrimSpace(payload.Body)
	env := payload.Env
	if env == nil {
		env = []settings.ActionEnvVar{}
	}

	if err := validateActionFields(name, payload.Kind, body, env); err != nil {
		return settings.Action{}, err
	}

	actionID, err := auth.NewUUID()
	if err != nil {
		return settings.Action{}, err
	}

	now := time.Now().UTC()
	return settings.Action{
		ID:          actionID,
		Name:        name,
		Description: description,
		Kind:        payload.Kind,
		Body:        body,
		Env:         env,
		Builtin:     false,
		CreatedAt:   now,
		UpdatedAt:   now,
	}, nil
}

func validateActionFields(
	name string,
	kind settings.ActionKind,
	body string,
	env []settings.ActionEnvVar,
) error {
	if name == "" {
		return errActionNameRequired
	}
	if body == "" {
		return errActionBodyRequired
	}
	if kind != settings.ActionKindShell && kind != settings.ActionKindScript {
		return errActionKindInvalid
	}
	for index := range env {
		env[index].Name = strings.TrimSpace(env[index].Name)
		if env[index].Name == "" || !envVarNamePattern.MatchString(env[index].Name) {
			return errors.New("environment variable name must match [A-Za-z_][A-Za-z0-9_]*")
		}
	}
	return nil
}

func findActionIndex(actions []settings.Action, actionID string) int {
	for index := range actions {
		if actions[index].ID == actionID {
			return index
		}
	}
	return -1
}