package server

import (
	"encoding/json"
	"net/http"
	"strconv"
	"strings"

	"forge.cadoles.com/Cadoles/emissary/internal/agent/metadata"
	"forge.cadoles.com/Cadoles/emissary/internal/datastore"
	"forge.cadoles.com/Cadoles/emissary/internal/jwk"
	"github.com/go-chi/chi"
	"github.com/pkg/errors"
	"gitlab.com/wpetit/goweb/api"
	"gitlab.com/wpetit/goweb/logger"
)

const (
	ErrCodeUnknownError     api.ErrorCode = "unknown-error"
	ErrCodeNotFound         api.ErrorCode = "not-found"
	ErrCodeInvalidSignature api.ErrorCode = "invalid-signature"
	ErrCodeConflict         api.ErrorCode = "conflict"
)

type registerAgentRequest struct {
	KeySet     json.RawMessage  `json:"keySet" validate:"required"`
	Metadata   []metadata.Tuple `json:"metadata" validate:"required"`
	Thumbprint string           `json:"thumbprint" validate:"required"`
	Signature  string           `json:"signature" validate:"required"`
}

func (s *Server) registerAgent(w http.ResponseWriter, r *http.Request) {
	registerAgentReq := &registerAgentRequest{}
	if ok := api.Bind(w, r, registerAgentReq); !ok {
		return
	}

	ctx := r.Context()

	keySet, err := jwk.Parse(registerAgentReq.KeySet)
	if err != nil {
		logger.Error(ctx, "could not parse key set", logger.E(errors.WithStack(err)))
		api.ErrorResponse(w, http.StatusInternalServerError, ErrCodeUnknownError, nil)

		return
	}

	ctx = logger.With(ctx, logger.F("agentThumbprint", registerAgentReq.Thumbprint))

	// Validate that the existing signature validates the request

	validSignature, err := jwk.Verify(keySet, registerAgentReq.Signature, registerAgentReq.Thumbprint, registerAgentReq.Metadata)
	if err != nil {
		logger.Error(ctx, "could not validate signature", logger.E(errors.WithStack(err)))
		api.ErrorResponse(w, http.StatusInternalServerError, ErrCodeUnknownError, nil)

		return
	}

	if !validSignature {
		logger.Error(ctx, "conflicting signature", logger.F("signature", registerAgentReq.Signature))
		api.ErrorResponse(w, http.StatusConflict, ErrCodeConflict, nil)

		return
	}

	metadata := metadata.FromSorted(registerAgentReq.Metadata)

	agent, err := s.agentRepo.Create(
		ctx,
		registerAgentReq.Thumbprint,
		keySet,
		metadata,
	)
	if err != nil {
		if !errors.Is(err, datastore.ErrAlreadyExist) {
			logger.Error(ctx, "could not create agent", logger.E(errors.WithStack(err)))
			api.ErrorResponse(w, http.StatusInternalServerError, ErrCodeUnknownError, nil)

			return
		}

		agents, _, err := s.agentRepo.Query(
			ctx,
			datastore.WithAgentQueryThumbprints(registerAgentReq.Thumbprint),
			datastore.WithAgentQueryLimit(1),
		)
		if err != nil {
			logger.Error(ctx, "could not retrieve agents", logger.E(errors.WithStack(err)))
			api.ErrorResponse(w, http.StatusInternalServerError, ErrCodeUnknownError, nil)

			return
		}

		if len(agents) == 0 {
			logger.Error(ctx, "could not retrieve matching agent", logger.E(errors.WithStack(err)))

			api.ErrorResponse(w, http.StatusInternalServerError, ErrCodeNotFound, nil)

			return
		}

		agentID := agents[0].ID

		agent, err = s.agentRepo.Get(ctx, agentID)
		if err != nil {
			logger.Error(
				ctx, "could not retrieve agent",
				logger.E(errors.WithStack(err)), logger.F("agentID", agentID),
			)
			api.ErrorResponse(w, http.StatusInternalServerError, ErrCodeUnknownError, nil)

			return
		}

		validSignature, err = jwk.Verify(agent.KeySet.Set, registerAgentReq.Signature, registerAgentReq.Thumbprint, registerAgentReq.Metadata)
		if err != nil {
			logger.Error(ctx, "could not validate signature using previous keyset", logger.E(errors.WithStack(err)))

			api.ErrorResponse(w, http.StatusConflict, ErrCodeConflict, nil)

			return
		}

		agent, err = s.agentRepo.Update(
			ctx, agents[0].ID,
			datastore.WithAgentUpdateKeySet(keySet),
			datastore.WithAgentUpdateMetadata(metadata),
			datastore.WithAgentUpdateThumbprint(registerAgentReq.Thumbprint),
		)
		if err != nil {
			logger.Error(ctx, "could not update agent", logger.E(errors.WithStack(err)))
			api.ErrorResponse(w, http.StatusInternalServerError, ErrCodeUnknownError, nil)

			return
		}
	}

	api.DataResponse(w, http.StatusCreated, struct {
		Agent *datastore.Agent `json:"agent"`
	}{
		Agent: agent,
	})
}

type updateAgentRequest struct {
	Status *datastore.AgentStatus `json:"status" validate:"omitempty,oneof=0 1 2 3"`
}

func (s *Server) updateAgent(w http.ResponseWriter, r *http.Request) {
	agentID, ok := getAgentID(w, r)
	if !ok {
		return
	}

	ctx := r.Context()

	updateAgentReq := &updateAgentRequest{}
	if ok := api.Bind(w, r, updateAgentReq); !ok {
		return
	}

	options := make([]datastore.AgentUpdateOptionFunc, 0)

	if updateAgentReq.Status != nil {
		options = append(options, datastore.WithAgentUpdateStatus(*updateAgentReq.Status))
	}

	agent, err := s.agentRepo.Update(
		ctx,
		datastore.AgentID(agentID),
		options...,
	)
	if err != nil {
		logger.Error(ctx, "could not update agent", logger.E(errors.WithStack(err)))
		api.ErrorResponse(w, http.StatusInternalServerError, ErrCodeUnknownError, nil)

		return
	}

	api.DataResponse(w, http.StatusOK, struct {
		Agent *datastore.Agent `json:"agent"`
	}{
		Agent: agent,
	})
}

func (s *Server) queryAgents(w http.ResponseWriter, r *http.Request) {
	limit, ok := getIntQueryParam(w, r, "limit", 10)
	if !ok {
		return
	}

	offset, ok := getIntQueryParam(w, r, "offset", 0)
	if !ok {
		return
	}

	options := []datastore.AgentQueryOptionFunc{
		datastore.WithAgentQueryLimit(int(limit)),
		datastore.WithAgentQueryOffset(int(offset)),
	}

	ids, ok := getIntSliceValues(w, r, "ids", nil)
	if !ok {
		return
	}

	if ids != nil {
		agentIDs := func(ids []int64) []datastore.AgentID {
			agentIDs := make([]datastore.AgentID, 0, len(ids))
			for _, id := range ids {
				agentIDs = append(agentIDs, datastore.AgentID(id))
			}

			return agentIDs
		}(ids)

		options = append(options, datastore.WithAgentQueryID(agentIDs...))
	}

	thumbprints, ok := getStringSliceValues(w, r, "thumbprints", nil)
	if !ok {
		return
	}

	if thumbprints != nil {
		options = append(options, datastore.WithAgentQueryThumbprints(thumbprints...))
	}

	statuses, ok := getIntSliceValues(w, r, "statuses", nil)
	if !ok {
		return
	}

	if statuses != nil {
		agentStatuses := func(statuses []int64) []datastore.AgentStatus {
			agentStatuses := make([]datastore.AgentStatus, 0, len(statuses))
			for _, status := range statuses {
				agentStatuses = append(agentStatuses, datastore.AgentStatus(status))
			}

			return agentStatuses
		}(statuses)

		options = append(options, datastore.WithAgentQueryStatus(agentStatuses...))
	}

	ctx := r.Context()

	agents, total, err := s.agentRepo.Query(
		ctx,
		options...,
	)
	if err != nil {
		logger.Error(ctx, "could not list agents", logger.E(errors.WithStack(err)))
		api.ErrorResponse(w, http.StatusInternalServerError, ErrCodeUnknownError, nil)

		return
	}

	api.DataResponse(w, http.StatusOK, struct {
		Agents []*datastore.Agent `json:"agents"`
		Total  int                `json:"total"`
	}{
		Agents: agents,
		Total:  total,
	})
}

func (s *Server) deleteAgent(w http.ResponseWriter, r *http.Request) {
	agentID, ok := getAgentID(w, r)
	if !ok {
		return
	}

	ctx := r.Context()

	err := s.agentRepo.Delete(
		ctx,
		datastore.AgentID(agentID),
	)
	if err != nil {
		if errors.Is(err, datastore.ErrNotFound) {
			api.ErrorResponse(w, http.StatusNotFound, ErrCodeNotFound, nil)

			return
		}

		logger.Error(ctx, "could not delete agent", logger.E(errors.WithStack(err)))
		api.ErrorResponse(w, http.StatusInternalServerError, ErrCodeUnknownError, nil)

		return
	}

	api.DataResponse(w, http.StatusOK, struct {
		AgentID datastore.AgentID `json:"agentId"`
	}{
		AgentID: datastore.AgentID(agentID),
	})
}

func (s *Server) getAgent(w http.ResponseWriter, r *http.Request) {
	agentID, ok := getAgentID(w, r)
	if !ok {
		return
	}

	ctx := r.Context()

	agent, err := s.agentRepo.Get(
		ctx,
		datastore.AgentID(agentID),
	)
	if err != nil {
		if errors.Is(err, datastore.ErrNotFound) {
			api.ErrorResponse(w, http.StatusNotFound, ErrCodeNotFound, nil)

			return
		}

		logger.Error(ctx, "could not get agent", logger.E(errors.WithStack(err)))
		api.ErrorResponse(w, http.StatusInternalServerError, ErrCodeUnknownError, nil)

		return
	}

	api.DataResponse(w, http.StatusOK, struct {
		Agent *datastore.Agent `json:"agent"`
	}{
		Agent: agent,
	})
}

func getAgentID(w http.ResponseWriter, r *http.Request) (datastore.AgentID, bool) {
	rawAgentID := chi.URLParam(r, "agentID")

	agentID, err := strconv.ParseInt(rawAgentID, 10, 64)
	if err != nil {
		logger.Error(r.Context(), "could not parse agent id", logger.E(errors.WithStack(err)))
		api.ErrorResponse(w, http.StatusBadRequest, api.ErrCodeMalformedRequest, nil)

		return 0, false
	}

	return datastore.AgentID(agentID), true
}

func getIntQueryParam(w http.ResponseWriter, r *http.Request, param string, defaultValue int64) (int64, bool) {
	rawValue := r.URL.Query().Get(param)
	if rawValue != "" {
		value, err := strconv.ParseInt(rawValue, 10, 64)
		if err != nil {
			logger.Error(r.Context(), "could not parse int param", logger.F("param", param), logger.E(errors.WithStack(err)))
			api.ErrorResponse(w, http.StatusBadRequest, api.ErrCodeMalformedRequest, nil)

			return 0, false
		}

		return value, true
	}

	return defaultValue, true
}

func getStringSliceValues(w http.ResponseWriter, r *http.Request, param string, defaultValue []string) ([]string, bool) {
	rawValue := r.URL.Query().Get(param)
	if rawValue != "" {
		values := strings.Split(rawValue, ",")

		return values, true
	}

	return defaultValue, true
}

func getIntSliceValues(w http.ResponseWriter, r *http.Request, param string, defaultValue []int64) ([]int64, bool) {
	rawValue := r.URL.Query().Get(param)

	if rawValue != "" {
		rawValues := strings.Split(rawValue, ",")
		values := make([]int64, 0, len(rawValues))

		for _, rv := range rawValues {
			value, err := strconv.ParseInt(rv, 10, 64)
			if err != nil {
				logger.Error(r.Context(), "could not parse int slice param", logger.F("param", param), logger.E(errors.WithStack(err)))
				api.ErrorResponse(w, http.StatusBadRequest, api.ErrCodeMalformedRequest, nil)

				return nil, false
			}

			values = append(values, value)
		}

		return values, true
	}

	return defaultValue, true
}