package api

import (
	"encoding/json"
	"errors"
	"fmt"
	"net/http"
	"strings"

	"gardomatic.kleiax.de/internal/platform/validate"
	"gardomatic.kleiax.de/internal/storage"
)

type locationInput struct {
	ParentID      *int            `json:"parent_id"`
	ClearParentID bool            `json:"clear_parent_id"`
	Name          *string         `json:"name"`
	Description   *string         `json:"description"`
	ImageData     *string         `json:"image_data"`
	ImageID       *int            `json:"image_id"`
	Kind          *string         `json:"kind"`
	AreaSQM       *float64        `json:"area_sqm"`
	SunExposure   *string         `json:"sun_exposure"`
	SoilCondition *string         `json:"soil_condition"`
	SoilReaction  *string         `json:"soil_reaction"`
	Attributes    json.RawMessage `json:"attributes"`
}

func (input locationInput) apply(location *storage.Location) {
	if input.ParentID != nil {
		location.ParentID = input.ParentID
	}
	if input.ClearParentID {
		location.ParentID = nil
	}
	if input.Name != nil {
		location.Name = strings.TrimSpace(*input.Name)
	}
	if input.Description != nil {
		location.Description = strings.TrimSpace(*input.Description)
	}
	if input.ImageData != nil {
		location.ImageData = *input.ImageData
	}
	if input.Kind != nil {
		location.Kind = strings.TrimSpace(*input.Kind)
	}
	if input.AreaSQM != nil {
		location.AreaSQM = input.AreaSQM
	}
	if input.SunExposure != nil {
		assignStringPointer(input.SunExposure, &location.SunExposure)
	}
	assignStringPointer(input.SoilCondition, &location.SoilCondition)
	assignStringPointer(input.SoilReaction, &location.SoilReaction)
	if len(input.Attributes) != 0 {
		location.Attributes = input.Attributes
	}
}

func (app *application) createLocationHandler(w http.ResponseWriter, r *http.Request) {
	gardenID, _ := app.readGardenIDParam(r)
	var input locationInput
	if err := app.readJSON(w, r, &input); err != nil {
		app.badRequestResponse(w, r, err)
		return
	}
	user, _ := app.contextGetAuthenticatedUser(r)
	location := storage.Location{GardenID: gardenID, Attributes: json.RawMessage(`{}`), CreatedBy: user.ID, UpdatedBy: user.ID}
	input.apply(&location)
	if !app.validateLocationForGarden(w, r, gardenID, location) {
		return
	}
	imageID, err := app.resolveImage(gardenID, location.ImageData, input.ImageID, user.ID, "location")
	if err != nil {
		app.badRequestResponse(w, r, err)
		return
	}
	location.ImageID = imageID
	location.ImageData = ""
	location, err = app.models.Locations.Insert(location)
	if err != nil {
		app.respondToEntityModelError(w, r, err)
		return
	}
	headers := make(http.Header)
	headers.Set("Location", fmt.Sprintf("/v1/gardens/%d/locations/%d", gardenID, location.ID))
	if err := app.writeJSON(w, http.StatusCreated, envelope{"location": location}, headers); err != nil {
		app.serverErrorResponse(w, r, err)
	}
}

func (app *application) listLocationsHandler(w http.ResponseWriter, r *http.Request) {
	gardenID, _ := app.readGardenIDParam(r)
	locations, err := app.models.Locations.GetAllForGarden(gardenID)
	if err != nil {
		app.serverErrorResponse(w, r, err)
		return
	}
	user, _ := app.contextGetAuthenticatedUser(r)
	member, _ := app.contextGetGardenMember(r)
	visible := locations[:0]
	for _, location := range locations {
		if location.CreatedBy == user.ID && member.Can(storage.GardenPermissionLocationReadOwn) || location.CreatedBy != user.ID && member.Can(storage.GardenPermissionLocationReadOther) {
			visible = append(visible, location)
		}
	}
	if err := app.writeJSON(w, http.StatusOK, envelope{"locations": visible}, nil); err != nil {
		app.serverErrorResponse(w, r, err)
	}
}

func (app *application) showLocationHandler(w http.ResponseWriter, r *http.Request) {
	gardenID, _ := app.readGardenIDParam(r)
	id, err := app.readIDParam(r)
	if err != nil {
		app.notFoundResponse(w, r)
		return
	}
	location, err := app.models.Locations.Get(gardenID, id)
	if err != nil {
		app.respondToEntityModelError(w, r, err)
		return
	}
	if !app.authorizeGardenResource(w, r, location.CreatedBy, storage.GardenPermissionLocationReadOwn, storage.GardenPermissionLocationReadOther) {
		return
	}
	if err := app.writeJSON(w, http.StatusOK, envelope{"location": location}, nil); err != nil {
		app.serverErrorResponse(w, r, err)
	}
}

func (app *application) updateLocationHandler(w http.ResponseWriter, r *http.Request) {
	gardenID, _ := app.readGardenIDParam(r)
	id, err := app.readIDParam(r)
	if err != nil {
		app.notFoundResponse(w, r)
		return
	}
	location, err := app.models.Locations.Get(gardenID, id)
	if err != nil {
		app.respondToEntityModelError(w, r, err)
		return
	}
	if !app.authorizeGardenResource(w, r, location.CreatedBy, storage.GardenPermissionLocationUpdateOwn, storage.GardenPermissionLocationUpdateOther) {
		return
	}
	var input locationInput
	if err := app.readJSON(w, r, &input); err != nil {
		app.badRequestResponse(w, r, err)
		return
	}
	previousImageID := location.ImageID
	previousImageData := location.ImageData
	input.apply(&location)
	user, _ := app.contextGetAuthenticatedUser(r)
	location.UpdatedBy = user.ID
	if !app.validateLocationForGarden(w, r, gardenID, location) {
		return
	}
	if input.ImageData != nil && *input.ImageData != previousImageData {
		location.ImageID, err = app.resolveImage(gardenID, *input.ImageData, input.ImageID, user.ID, "location")
		if err != nil {
			app.badRequestResponse(w, r, err)
			return
		}
	}
	location.ImageData = ""
	location, err = app.models.Locations.Update(gardenID, location)
	if err != nil {
		app.respondToEntityModelError(w, r, err)
		return
	}
	if err = app.recordImageAssignment(storage.ImageAssignment{GardenID: gardenID, EntityType: "location", EntityID: location.ID, PreviousImageID: previousImageID, ImageID: location.ImageID, ChangedBy: user.ID}); err != nil {
		app.serverErrorResponse(w, r, err)
		return
	}
	if err := app.writeJSON(w, http.StatusOK, envelope{"location": location}, nil); err != nil {
		app.serverErrorResponse(w, r, err)
	}
}

func (app *application) deleteLocationHandler(w http.ResponseWriter, r *http.Request) {
	gardenID, _ := app.readGardenIDParam(r)
	id, err := app.readIDParam(r)
	if err != nil {
		app.notFoundResponse(w, r)
		return
	}
	location, err := app.models.Locations.Get(gardenID, id)
	if err != nil {
		app.respondToEntityModelError(w, r, err)
		return
	}
	if !app.authorizeGardenResource(w, r, location.CreatedBy, storage.GardenPermissionLocationDeleteOwn, storage.GardenPermissionLocationDeleteOther) {
		return
	}
	if err := app.models.Locations.Delete(gardenID, id); err != nil {
		app.respondToEntityModelError(w, r, err)
		return
	}
	w.WriteHeader(http.StatusNoContent)
}

func (app *application) validateLocationForGarden(w http.ResponseWriter, r *http.Request, gardenID int, location storage.Location) bool {
	v := validate.New()
	validateImageData(v, location.ImageData)
	storage.ValidateLocation(v, location)
	if location.ParentID != nil && *location.ParentID > 0 && *location.ParentID != location.ID {
		if _, err := app.models.Locations.Get(gardenID, *location.ParentID); err != nil {
			if errors.Is(err, storage.ErrRecordNotFound) {
				v.AddError("parent_id", "must refer to a location in this garden")
			} else {
				app.serverErrorResponse(w, r, err)
				return false
			}
		}
	}
	if v.Valid() && location.ParentID != nil && location.ID > 0 {
		locations, err := app.models.Locations.GetAllForGarden(gardenID)
		if err != nil {
			app.serverErrorResponse(w, r, err)
			return false
		}
		parents := make(map[int]*int, len(locations))
		for i := range locations {
			parents[locations[i].ID] = locations[i].ParentID
		}
		seen := map[int]bool{}
		for current := location.ParentID; current != nil; current = parents[*current] {
			if *current == location.ID || seen[*current] {
				v.AddError("parent_id", "must not create a cycle")
				break
			}
			seen[*current] = true
		}
	}
	if !v.Valid() {
		app.failedValidationResponse(w, r, v.Errors)
		return false
	}
	return true
}