package cif

import (
	"fmt"
	"time"

	"git.fjla.uk/owlboard/go-types/pkg/upstreamApi"
	"git.fjla.uk/owlboard/timetable-mgr/dbAccess"
	"git.fjla.uk/owlboard/timetable-mgr/log"
	"go.uber.org/zap"
)

// Evaluates last and new metadata and determines whether an update is required.
// // If last update == "full" && lastupdate after yesterday at 0600, run update.
// // Beyond that condition, comparisons are made between old and new metadata.
func checkMetadata(oldMeta *dbAccess.CifMetadata, newMeta *upstreamApi.JsonTimetableV1) (reason string, updateRequired bool) {
	// Handle nil pointer - although this should be resolved in the calling function in ideal situations
	if oldMeta == nil || newMeta == nil {
		log.Debug("oldMeta or newMeta is a nil pointer.")
		return "nil-pointer", false
	}

	if !isTimestampWithinLastFiveDays(newMeta.Timestamp) {
		log.Debug("Downloaded CIF File not produced in last five days", zap.Time("file_timestamp", time.Unix(newMeta.Timestamp, 0)))
		return "downloaded-data-is-too-old", false
	}

	// Handle non-matching sequence numbers between full and daily download types
	//	if isAfterYesterdayAt0600(oldMeta.LastUpdate) {
	//		return "last-update-full", true
	//	}

	// Check that the new metadata sequence is as expected.
	if newMeta.Metadata.Sequence == oldMeta.LastSequence+1 {
		log.Debug("Sequence numbers", zap.Int64("New", newMeta.Metadata.Sequence), zap.Int64("Old", oldMeta.LastSequence))
		return "correct-sequence", true
	} else {
		s := fmt.Sprintf("incorrect sequence, Old: %d, New: %d, Expected New: %d", oldMeta.LastSequence, newMeta.Metadata.Sequence, oldMeta.LastSequence+1)
		return s, false
	}
}

// Evaluates whether the given time is after yesterday at 0600
func isAfterYesterdayAt0600(t time.Time) bool {
	yesterday0600 := time.Now().In(londonTimezone).AddDate(0, 0, -1)
	yesterday0600 = time.Date(yesterday0600.Year(), yesterday0600.Month(), yesterday0600.Day(), 6, 0, 0, 0, time.UTC)
	return t.After(yesterday0600)
}

// Accepts the JsonTimetableV1 struct which contains CIF File metadata and produces a DB Ready struct.
func generateMetadata(header *upstreamApi.JsonTimetableV1) *dbAccess.CifMetadata {
	newMetadata := dbAccess.CifMetadata{
		Doctype:       dbAccess.Doctype,
		LastTimestamp: header.Timestamp,
		LastUpdate:    time.Now().In(londonTimezone),
		LastSequence:  header.Metadata.Sequence,
	}

	return &newMetadata
}

// Accepts a unix timestamp and returns true if the timestamp is within the last five days, else false
func isTimestampWithinLastFiveDays(ts int64) bool {
	timestamp := time.Unix(ts, 0)
	timeNow := time.Now()
	fiveDaysAgo := timeNow.AddDate(0, 0, -5)

	return !timestamp.Before(fiveDaysAgo)
}