package query

import (
	"database/sql"
	"errors"

	"github.com/AmanTahiliani/box-box/internal/models"
	"github.com/AmanTahiliani/box-box/internal/store"
)

// Service assembles store-backed read models.
type Service struct {
	store *store.Store
}

// NewService creates a query service over a domain store.
func NewService(st *store.Store) *Service {
	return &Service{store: st}
}

// EnrichedResult is a session result with driver identity fields.
type EnrichedResult struct {
	models.SessionResult
	NameAcronym string `json:"name_acronym"`
	FullName    string `json:"full_name"`
	TeamName    string `json:"team_name"`
	TeamColour  string `json:"team_colour"`
}

// EnrichedGrid is a starting grid row with driver identity fields.
type EnrichedGrid struct {
	models.StartingGrid
	NameAcronym string `json:"name_acronym"`
	FullName    string `json:"full_name"`
	TeamName    string `json:"team_name"`
	TeamColour  string `json:"team_colour"`
}

// RaceHub is the local-first Race Hub read model for one session.
type RaceHub struct {
	Source       string                 `json:"source"`
	SessionKey   int                    `json:"session_key"`
	Datasets     map[string]DatasetInfo `json:"datasets"`
	Meeting      *models.Meeting        `json:"meeting,omitempty"`
	Session      *models.Session        `json:"session,omitempty"`
	Drivers      []models.Driver        `json:"drivers"`
	Results      []EnrichedResult       `json:"results"`
	StartingGrid []EnrichedGrid         `json:"starting_grid"`
}

// GetRaceHub loads ingested Race Hub datasets for a session from the local store.
func (s *Service) GetRaceHub(sessionKey int) (RaceHub, error) {
	hub := RaceHub{
		SessionKey: sessionKey,
		Datasets: map[string]DatasetInfo{
			"meeting":       missingDataset(),
			"session":       missingDataset(),
			"drivers":       missingDataset(),
			"results":       missingDataset(),
			"starting_grid": missingDataset(),
		},
		Drivers:      []models.Driver{},
		Results:      []EnrichedResult{},
		StartingGrid: []EnrichedGrid{},
	}

	sess, err := s.store.GetSession(sessionKey)
	if err != nil {
		if errors.Is(err, sql.ErrNoRows) {
			hub.Source = ResponseSourceNone
			return hub, nil
		}
		return RaceHub{}, err
	}

	sessionModel := sessionToModel(sess)
	hub.Session = &sessionModel
	hub.Datasets["session"] = availableLocal(1)

	meeting, err := s.store.GetMeeting(sess.MeetingKey)
	if err != nil {
		if !errors.Is(err, sql.ErrNoRows) {
			return RaceHub{}, err
		}
	} else {
		meetingModel := meetingToModel(meeting)
		hub.Meeting = &meetingModel
		hub.Datasets["meeting"] = availableLocal(1)
	}

	driverLinks, err := s.store.ListSessionDrivers(sessionKey)
	if err != nil {
		return RaceHub{}, err
	}
	if len(driverLinks) > 0 {
		drivers := make([]models.Driver, 0, len(driverLinks))
		for _, link := range driverLinks {
			d, err := s.store.GetDriver(link.DriverNumber)
			if err != nil && !errors.Is(err, sql.ErrNoRows) {
				return RaceHub{}, err
			}
			drivers = append(drivers, driverToModel(sessionKey, sess.MeetingKey, link, d))
		}
		hub.Drivers = drivers
		hub.Datasets["drivers"] = availableLocal(len(drivers))
	}

	driverByNumber := make(map[int]models.Driver, len(hub.Drivers))
	for _, d := range hub.Drivers {
		driverByNumber[d.DriverNumber] = d
	}

	results, err := s.store.ListSessionResults(sessionKey)
	if err != nil {
		return RaceHub{}, err
	}
	if len(results) > 0 {
		enriched := make([]EnrichedResult, 0, len(results))
		for _, r := range results {
			e := EnrichedResult{SessionResult: resultToModel(r)}
			if d, ok := driverByNumber[r.DriverNumber]; ok {
				e.NameAcronym = d.NameAcronym
				e.FullName = d.FullName
				e.TeamName = d.TeamName
				e.TeamColour = d.TeamColour
			}
			enriched = append(enriched, e)
		}
		hub.Results = enriched
		hub.Datasets["results"] = availableLocal(len(enriched))
	}

	grid, err := s.store.ListStartingGrid(sessionKey)
	if err != nil {
		return RaceHub{}, err
	}
	if len(grid) > 0 {
		enriched := make([]EnrichedGrid, 0, len(grid))
		for _, g := range grid {
			e := EnrichedGrid{StartingGrid: gridToModel(g)}
			if d, ok := driverByNumber[g.DriverNumber]; ok {
				e.NameAcronym = d.NameAcronym
				e.FullName = d.FullName
				e.TeamName = d.TeamName
				e.TeamColour = d.TeamColour
			}
			enriched = append(enriched, e)
		}
		hub.StartingGrid = enriched
		hub.Datasets["starting_grid"] = availableLocal(len(enriched))
	}

	hub.Source = responseSource(hub.Datasets)
	return hub, nil
}