package service

import (
	"context"
	"fmt"
	"strconv"
	"strings"

	"github.com/cortezaproject/corteza/server/pkg/dal"
	"github.com/cortezaproject/corteza/server/pkg/errors"
	"github.com/cortezaproject/corteza/server/pkg/locale"

	"github.com/cortezaproject/corteza/server/pkg/actionlog"
	"github.com/cortezaproject/corteza/server/pkg/filter"
	"github.com/cortezaproject/corteza/server/pkg/label"
	"github.com/cortezaproject/corteza/server/store"
	"github.com/cortezaproject/corteza/server/system/reporting"
	"github.com/cortezaproject/corteza/server/system/types"
	"github.com/modern-go/reflect2"
	"github.com/spf13/cast"
)

type (
	report struct {
		ac        reportAccessController
		eventbus  eventDispatcher
		actionlog actionlog.Recorder
		store     store.Storer
		locale    locale.Locale

		users UserService

		pipelineRunner pipelineRunner
	}

	reportAccessController interface {
		CanSearchReports(context.Context) bool
		CanCreateReport(context.Context) bool
		CanReadReport(context.Context, *types.Report) bool
		CanUpdateReport(context.Context, *types.Report) bool
		CanDeleteReport(context.Context, *types.Report) bool
		CanRunReport(context.Context, *types.Report) bool
	}

	pipelineRunner interface {
		Run(context.Context, dal.Pipeline) (dal.Iterator, error)
		Dryrun(context.Context, dal.Pipeline) error
		FindModel(dal.ModelRef) *dal.Model
	}
)

// Report is a default report service initializer
func Report(s store.Storer, ac reportAccessController, al actionlog.Recorder, eb eventDispatcher) *report {
	return &report{
		store:     s,
		ac:        ac,
		actionlog: al,
		eventbus:  eb,
		locale:    locale.Global(),

		users: DefaultUser,

		pipelineRunner: dal.Service(),
	}
}

func (svc *report) LookupByID(ctx context.Context, ID uint64) (report *types.Report, err error) {
	var (
		aaProps = &reportActionProps{report: &types.Report{ID: ID}}
	)

	err = func() error {
		if report, err = loadReport(ctx, svc.store, ID); err != nil {
			return ReportErrInvalidID().Wrap(err)
		}

		if !svc.ac.CanReadReport(ctx, report) {
			return ReportErrNotAllowedToRead()
		}

		return nil
	}()

	return report, svc.recordAction(ctx, aaProps, ReportActionLookup, err)
}

func (svc *report) Search(ctx context.Context, rf types.ReportFilter) (rr types.ReportSet, f types.ReportFilter, err error) {
	var (
		aaProps = &reportActionProps{filter: &rf}
	)

	// For each fetched item, store backend will check if it is valid or not
	rf.Check = func(res *types.Report) (bool, error) {
		if !svc.ac.CanReadReport(ctx, res) {
			return false, nil
		}

		return true, nil
	}

	err = func() error {
		if !svc.ac.CanSearchReports(ctx) {
			return ReportErrNotAllowedToSearch()
		}

		if len(rf.Labels) > 0 {
			rf.LabeledIDs, err = label.Search(
				ctx,
				svc.store,
				types.Report{}.LabelResourceKind(),
				rf.Labels,
			)

			if err != nil {
				return err
			}

			// labels specified but no labeled resources found
			if len(rf.LabeledIDs) == 0 {
				return nil
			}
		}

		if rr, f, err = store.SearchReports(ctx, svc.store, rf); err != nil {
			return err
		}

		if err = label.Load(ctx, svc.store, toLabeledReports(rr)...); err != nil {
			return err
		}

		return nil

	}()

	return rr, f, svc.recordAction(ctx, aaProps, ReportActionSearch, err)
}

func (svc *report) Create(ctx context.Context, new *types.Report) (report *types.Report, err error) {
	var (
		aaProps = &reportActionProps{report: new}
	)

	err = func() (err error) {
		if !svc.ac.CanCreateReport(ctx) {
			return ReportErrNotAllowedToCreate()
		}

		// if err = svc.eventbus.WaitFor(ctx, event.ReportBeforeCreate(new, nil)); err != nil {
		// 	return
		// }

		// Set new values after beforeCreate events are emitted
		new.ID = nextID()
		new.CreatedAt = *now()

		if new.Meta == nil {
			new.Meta = &types.ReportMeta{}
		}

		new = svc.setIDs(new)

		aaProps.setNew(new)

		if err = store.CreateReport(ctx, svc.store, new); err != nil {
			return
		}

		if err = label.Create(ctx, svc.store, new); err != nil {
			return
		}

		report = new

		// _ = svc.eventbus.WaitFor(ctx, event.ReportAfterCreate(new, nil))
		return nil
	}()

	return report, svc.recordAction(ctx, aaProps, ReportActionCreate, err)
}

func (svc *report) Update(ctx context.Context, upd *types.Report) (report *types.Report, err error) {
	var (
		aaProps = &reportActionProps{update: upd}
	)

	err = func() (err error) {
		if report, err = loadReport(ctx, svc.store, upd.ID); err != nil {
			return
		}

		aaProps.setReport(report)

		if !svc.ac.CanUpdateReport(ctx, report) {
			return ReportErrNotAllowedToUpdate()
		}

		// Test if stale (update has an older version of data)
		if isStale(upd.UpdatedAt, report.UpdatedAt, report.CreatedAt) {
			return ReportErrStaleData()
		}

		// if err = svc.eventbus.WaitFor(ctx, event.ReportBeforeUpdate(upd, report)); err != nil {
		// 	return
		// }

		// Assign changed values after afterUpdate events are emitted
		report.Handle = upd.Handle
		report.Meta = upd.Meta
		report.Scenarios = upd.Scenarios
		report.Sources = upd.Sources
		report.Blocks = upd.Blocks
		report.UpdatedAt = now()

		if upd.Meta != nil {
			report.Meta = upd.Meta
		}

		report = svc.setIDs(report)

		if err = store.UpdateReport(ctx, svc.store, report); err != nil {
			return err
		}

		if label.Changed(report.Labels, upd.Labels) {
			if err = label.Update(ctx, svc.store, upd); err != nil {
				return
			}
			report.Labels = upd.Labels
		}

		// _ = svc.eventbus.WaitFor(ctx, event.ReportAfterUpdate(upd, report))
		return nil
	}()

	return report, svc.recordAction(ctx, aaProps, ReportActionUpdate, err)
}

func (svc *report) Delete(ctx context.Context, ID uint64) (err error) {
	var (
		aaProps = &reportActionProps{}
		report  *types.Report
	)

	err = func() (err error) {
		if report, err = loadReport(ctx, svc.store, ID); err != nil {
			return
		}

		aaProps.setReport(report)

		if !svc.ac.CanDeleteReport(ctx, report) {
			return ReportErrNotAllowedToDelete()
		}

		// if err = svc.eventbus.WaitFor(ctx, event.ReportBeforeDelete(nil, report)); err != nil {
		// 	return
		// }

		report.DeletedAt = now()
		if err = store.UpdateReport(ctx, svc.store, report); err != nil {
			return
		}

		// _ = svc.eventbus.WaitFor(ctx, event.ReportAfterDelete(nil, report))
		return nil
	}()

	return svc.recordAction(ctx, aaProps, ReportActionDelete, err)
}

func (svc *report) Undelete(ctx context.Context, ID uint64) (err error) {
	var (
		aaProps = &reportActionProps{}
		report  *types.Report
	)

	err = func() (err error) {
		if report, err = loadReport(ctx, svc.store, ID); err != nil {
			return
		}

		aaProps.setReport(report)

		if !svc.ac.CanDeleteReport(ctx, report) {
			return ReportErrNotAllowedToUndelete()
		}

		// if err = svc.eventbus.WaitFor(ctx, event.ReportBeforeUndelete(nil, app)); err != nil {
		// 	return
		// }

		report.DeletedAt = nil
		if err = store.UpdateReport(ctx, svc.store, report); err != nil {
			return
		}

		// _ = svc.eventbus.WaitFor(ctx, event.ReportAfterUndelete(nil, app))
		return nil
	}()

	return svc.recordAction(ctx, aaProps, ReportActionUndelete, err)
}

// @todo actionlog?
func (svc *report) Describe(ctx context.Context, src types.ReportDataSourceSet, st types.ReportStepSet, sources ...string) (out []reporting.FrameDescription, err error) {
	out = make([]reporting.FrameDescription, 0, len(sources)*2)

	err = func() (err error) {
		if !svc.ac.CanCreateReport(ctx) {
			return ReportErrNotAllowedToCreate()
		}

		ss := src.ReportSteps()
		ss = append(ss, st...)

		out, err = reporting.Describe(ctx, svc.pipelineRunner, ss, sources)
		return err
	}()

	return out, err
}

func (svc *report) Run(ctx context.Context, reportID uint64, dd reporting.FrameDefinitionSet) (_ []*reporting.Frame, err error) {
	var (
		aaProps = &reportActionProps{}

		iter dal.Iterator
		ff   []*reporting.Frame
		out  = make([]*reporting.Frame, 0, 4)
	)

	err = func() (err error) {
		// Load the report
		r, err := loadReport(ctx, svc.store, reportID)
		if err != nil {
			return err
		}

		// Access control
		if !svc.ac.CanRunReport(ctx, r) {
			return ReportErrNotAllowedToRun()
		}

		// Get all of the steps
		ss := r.Sources.ReportSteps()
		ss = append(ss, r.Blocks.ReportSteps()...)

		// Prepare a set of runs for the provided definitions
		runs, err := reporting.Runs(svc.pipelineRunner, ss, dd)
		if err != nil {
			return
		}

		// Run the reports and produce the frames
		// @todo this can be ran in paralel
		for _, run := range runs {
			err = func() (err error) {
				iter, err = svc.pipelineRunner.Run(ctx, run.Pipeline)
				if err != nil {
					return
				}
				defer iter.Close()

				ff, err = reporting.Frames(ctx, iter, run)
				if err != nil {
					return
				}

				err = svc.enhance(ctx, ff)
				if err != nil {
					return
				}

				out = append(out, ff...)
				return
			}()

			if err != nil {
				return
			}
		}

		return nil
	}()

	return out, svc.recordAction(ctx, aaProps, ReportActionRun, err)
}

// enhance is a temporary function that enriches the output to satisfy some current requirements.
// @todo extend core implementation to support such operatons
//
// - userID is replaced by the user name || username || email || handle || userID
func (svc *report) enhance(ctx context.Context, ff []*reporting.Frame) (err error) {
	// Preload sys users
	uIndex := make(map[uint64]*types.User)
	uu, uf, err := svc.users.Find(ctx, types.UserFilter{Paging: filter.Paging{Limit: 1024}})
	if err != nil {
		return
	}
	hasMore := uf.NextPage != nil
	for i := range uu {
		uIndex[uu[i].ID] = uu[i]
	}

	var uID uint64
	for _, f := range ff {
		userCols := make([]int, 0, len(f.Columns))
		for i, c := range f.Columns {
			// Translate system columns
			if c.System {
				pp := strings.Split(c.Name, ".")
				c.Label = svc.locale.T(ctx, "compose", fmt.Sprintf("field.system.%s", pp[len(pp)-1]))
				f.Columns[i] = c
			}

			// Collect user columns to replace IDs with labels
			if c.Kind != "User" {
				continue
			}
			userCols = append(userCols, i)
		}

		for _, r := range f.Rows {
			for _, ci := range userCols {
				col := r[ci]
				if reflect2.IsNil(col) {
					continue
				}
				uID, err = cast.ToUint64E(col)
				if err != nil {
					continue
				}

				user, ok := uIndex[uID]
				if !ok && hasMore {
					user, err = svc.users.FindByID(ctx, uID)
					if err != nil && err != store.ErrNotFound {
						return
					}
				}

				if user == nil {
					continue
				} else if _, ok := uIndex[uID]; !ok {
					uIndex[uID] = user
				}

				if usr, ok := uIndex[uID]; ok {
					r[ci] = strconv.FormatUint(uID, 10)
					if usr.Name != "" {
						r[ci] = usr.Name
					} else if usr.Username != "" {
						r[ci] = usr.Username
					} else if usr.Email != "" {
						r[ci] = usr.Email
					} else if usr.Handle != "" {
						r[ci] = usr.Handle
					}
				}
			}
		}
	}

	return err
}

func (svc *report) setIDs(r *types.Report) *types.Report {
	// scenarios
	for _, s := range r.Scenarios {
		if s.ScenarioID == 0 {
			s.ScenarioID = nextID()
		}
	}

	// blocks
	for _, b := range r.Blocks {
		if b.BlockID == 0 {
			b.BlockID = nextID()
		}

		// elements
		for _, elRaw := range b.Elements {
			el, ok := elRaw.(map[string]interface{})
			if !ok {
				continue
			}

			elID, ok := el["elementID"]
			sElID := cast.ToString(elID)
			if sElID != "" && sElID != "0" {
				continue
			}
			if cast.ToUint64(elID) != 0 {
				continue
			}

			el["elementID"] = strconv.FormatUint(nextID(), 10)
		}
	}

	return r
}

func loadReport(ctx context.Context, s store.Reports, ID uint64) (res *types.Report, err error) {
	if ID == 0 {
		return nil, ReportErrInvalidID()
	}

	if res, err = store.LookupReportByID(ctx, s, ID); errors.IsNotFound(err) {
		return nil, ReportErrNotFound()
	}

	return
}

// toLabeledReports converts to []label.LabeledResource
//
// This function is auto-generated.
func toLabeledReports(set []*types.Report) []label.LabeledResource {
	if len(set) == 0 {
		return nil
	}

	ll := make([]label.LabeledResource, len(set))
	for i := range set {
		ll[i] = set[i]
	}

	return ll
}