package api

import (
	"errors"
	"net/http"
	"strconv"

	"github.com/go-chi/chi/v5"
	"github.com/jackc/pgx/v5"
	"github.com/jackc/pgx/v5/pgtype"

	"git.fabledsword.com/bvandeusen/minstrel/internal/apierror"
	"git.fabledsword.com/bvandeusen/minstrel/internal/db/dbq"
	"git.fabledsword.com/bvandeusen/minstrel/internal/musicbrainz"
	"git.fabledsword.com/bvandeusen/minstrel/internal/wanted"
)

// The wanted list's admin surface (M502 #5520): wants, follows and
// release-type profiles.

// wantView is one row of GET /api/admin/wanted.
type wantView struct {
	ID               string   `json:"id"`
	ReleaseGroupMBID string   `json:"release_group_mbid"`
	Title            string   `json:"title"`
	ArtistMBID       string   `json:"artist_mbid"`
	ArtistName       string   `json:"artist_name"`
	ArtistID         string   `json:"artist_id,omitempty"`
	PrimaryType      string   `json:"primary_type"`
	SecondaryTypes   []string `json:"secondary_types"`
	Year             string   `json:"year"`
	Reason           string   `json:"reason"`
	RequestedBy      string   `json:"requested_by,omitempty"`
	AlbumID          string   `json:"album_id,omitempty"`
	WantedAt         string   `json:"wanted_at"`
	HeldAt           *string  `json:"held_at"`
	ImageURL         string   `json:"image_url"`
}

// wantCounts sizes each tab of the Wanted page.
type wantCounts struct {
	Wanted    int64 `json:"wanted"`
	Missing   int64 `json:"missing"`
	Held      int64 `json:"held"`
	Following int64 `json:"following"`
}

type wantsPage struct {
	Items  []wantView `json:"items"`
	Total  int64      `json:"total"`
	Limit  int        `json:"limit"`
	Offset int        `json:"offset"`
	Counts wantCounts `json:"counts"`
}

const wantsPageSize = 50

// handleListWants implements GET /api/admin/wanted?state=wanted|missing|held&offset=.
// wanted is everything open but missing files; held is newest first.
func (h *handlers) handleListWants(w http.ResponseWriter, r *http.Request) {
	state := r.URL.Query().Get("state")
	if state == "" {
		state = "wanted"
	}
	if state != "wanted" && state != "missing" && state != "held" {
		writeErr(w, apierror.BadRequest("bad_state", "state must be wanted, missing or held"))
		return
	}
	offset, _ := strconv.Atoi(r.URL.Query().Get("offset"))
	if offset < 0 {
		offset = 0
	}
	q := dbq.New(h.pool)
	rows, err := q.ListWants(r.Context(), dbq.ListWantsParams{State: state, Skip: int32(offset), MaxRows: wantsPageSize})
	if err != nil {
		writeErrWithLog(w, h.logger, "admin wanted: list", apierror.Internal(err))
		return
	}
	counts, err := q.CountWants(r.Context())
	if err != nil {
		writeErrWithLog(w, h.logger, "admin wanted: count", apierror.Internal(err))
		return
	}
	out := wantsPage{
		Items: make([]wantView, 0, len(rows)), Limit: wantsPageSize, Offset: offset,
		Counts: wantCounts{Wanted: counts.Wanted, Missing: counts.Missing, Held: counts.Held, Following: counts.Following},
	}
	switch state {
	case "missing":
		out.Total = counts.Missing
	case "held":
		out.Total = counts.Held
	default:
		out.Total = counts.Wanted
	}
	for _, row := range rows {
		v := wantView{
			ID: uuidToString(row.ID), ReleaseGroupMBID: row.ReleaseGroupMbid, Title: row.Title,
			ArtistMBID: row.ArtistMbid, ArtistName: row.ArtistName,
			PrimaryType: row.PrimaryType, SecondaryTypes: row.SecondaryTypes,
			Year: first4(row.FirstReleaseDate), Reason: row.Reason,
			WantedAt: formatTimestamp(row.WantedAt),
			ImageURL: groupArtURL(musicbrainz.ReleaseGroup{MBID: row.ReleaseGroupMbid, Title: row.Title, ArtistCredit: row.ArtistName}),
		}
		if row.LibraryArtistID.Valid {
			v.ArtistID = uuidToString(row.LibraryArtistID)
		}
		if row.AlbumID.Valid {
			v.AlbumID = uuidToString(row.AlbumID)
		}
		if row.RequestedBy != nil {
			v.RequestedBy = *row.RequestedBy
		}
		if row.FulfilledAt.Valid {
			held := formatTimestamp(row.FulfilledAt)
			v.HeldAt = &held
		}
		if v.SecondaryTypes == nil {
			v.SecondaryTypes = []string{}
		}
		out.Items = append(out.Items, v)
	}
	writeJSON(w, http.StatusOK, out)
}

func first4(date string) string {
	if len(date) < 4 {
		return ""
	}
	return date[:4]
}

// handleRemoveWant implements DELETE /api/admin/wanted/{id}.
func (h *handlers) handleRemoveWant(w http.ResponseWriter, r *http.Request) {
	id, ok := requireURLUUID(w, r, "id")
	if !ok {
		return
	}
	removed, err := h.wanted.RemoveWant(r.Context(), id)
	if err != nil {
		writeErrWithLog(w, h.logger, "admin wanted: remove", apierror.Internal(err))
		return
	}
	if !removed {
		writeErr(w, apierror.NotFound("want"))
		return
	}
	w.WriteHeader(http.StatusNoContent)
}

// followView is a followed artist.
type followView struct {
	ArtistMBID  string  `json:"artist_mbid"`
	ArtistName  string  `json:"artist_name"`
	ArtistID    string  `json:"artist_id,omitempty"`
	ProfileID   string  `json:"profile_id"`
	ProfileName string  `json:"profile_name"`
	FollowedAt  string  `json:"followed_at"`
	CheckedAt   *string `json:"checked_at"`
	OpenWants   int64   `json:"open_wants"`
	ImageURL    string  `json:"image_url"`
}

// handleListFollows implements GET /api/admin/follows.
func (h *handlers) handleListFollows(w http.ResponseWriter, r *http.Request) {
	rows, err := dbq.New(h.pool).ListFollows(r.Context())
	if err != nil {
		writeErrWithLog(w, h.logger, "admin follows: list", apierror.Internal(err))
		return
	}
	out := make([]followView, 0, len(rows))
	for _, f := range rows {
		v := followView{
			ArtistMBID: f.ArtistMbid, ArtistName: f.ArtistName,
			ProfileID: uuidToString(f.ProfileID), ProfileName: f.ProfileName,
			FollowedAt: formatTimestamp(f.FollowedAt), OpenWants: f.OpenWants,
			ImageURL: artistArtURL(f.ArtistMbid, f.ArtistName),
		}
		if f.ArtistID.Valid {
			v.ArtistID = uuidToString(f.ArtistID)
		}
		if f.CheckedAt.Valid {
			checked := formatTimestamp(f.CheckedAt)
			v.CheckedAt = &checked
		}
		out = append(out, v)
	}
	writeJSON(w, http.StatusOK, out)
}

// followStateView answers whether one artist is followed, for the control on
// an artist page.
type followStateView struct {
	Following   bool   `json:"following"`
	ProfileID   string `json:"profile_id,omitempty"`
	ProfileName string `json:"profile_name,omitempty"`
}

// handleGetFollow implements GET /api/admin/follows/{mbid}.
func (h *handlers) handleGetFollow(w http.ResponseWriter, r *http.Request) {
	f, err := dbq.New(h.pool).GetFollow(r.Context(), chi.URLParam(r, "mbid"))
	if errors.Is(err, pgx.ErrNoRows) {
		writeJSON(w, http.StatusOK, followStateView{})
		return
	}
	if err != nil {
		writeErrWithLog(w, h.logger, "admin follows: get", apierror.Internal(err))
		return
	}
	writeJSON(w, http.StatusOK, followStateView{
		Following: true, ProfileID: uuidToString(f.ProfileID), ProfileName: f.ProfileName,
	})
}

type putFollowBody struct {
	ArtistName   string `json:"artist_name"`
	ProfileID    string `json:"profile_id"`
	WantExisting bool   `json:"want_existing"`
}

// handlePutFollow implements PUT /api/admin/follows/{mbid}: follow an artist,
// or change the profile it is followed on. want_existing also wants what the
// artist has already released that the profile passes and isn't held.
func (h *handlers) handlePutFollow(w http.ResponseWriter, r *http.Request) {
	admin, ok := requireUser(w, r)
	if !ok {
		return
	}
	var body putFollowBody
	if !decodeBody(w, r, &body) {
		return
	}
	var profile pgtype.UUID
	if body.ProfileID != "" {
		if profile, ok = parseUUID(body.ProfileID); !ok {
			writeErr(w, apierror.BadRequest("bad_profile", "profile_id is not an id"))
			return
		}
	}
	mbid := chi.URLParam(r, "mbid")
	if _, err := h.wanted.Follow(r.Context(), wanted.FollowParams{
		ArtistMBID: mbid, ArtistName: body.ArtistName, ProfileID: profile,
		By: admin.ID, WantExisting: body.WantExisting,
	}); err != nil {
		switch {
		case errors.Is(err, wanted.ErrNotFollowable):
			writeErr(w, apierror.BadRequest("not_followable", "Various Artists and MusicBrainz placeholders can't be followed"))
		case errors.Is(err, wanted.ErrProfileNotFound):
			writeErr(w, apierror.BadRequest("profile_not_found", "no such profile"))
		default:
			writeErrWithLog(w, h.logger, "admin follows: put", apierror.Internal(err))
		}
		return
	}
	h.handleGetFollow(w, r)
}

// handleDeleteFollow implements DELETE /api/admin/follows/{mbid}. What the
// follow already wanted stays on the list.
func (h *handlers) handleDeleteFollow(w http.ResponseWriter, r *http.Request) {
	removed, err := h.wanted.Unfollow(r.Context(), chi.URLParam(r, "mbid"))
	if err != nil {
		writeErrWithLog(w, h.logger, "admin follows: delete", apierror.Internal(err))
		return
	}
	if !removed {
		writeErr(w, apierror.NotFound("follow"))
		return
	}
	w.WriteHeader(http.StatusNoContent)
}

// releaseProfileView is a release-type profile.
type releaseProfileView struct {
	ID             string   `json:"id"`
	Name           string   `json:"name"`
	PrimaryTypes   []string `json:"primary_types"`
	SecondaryTypes []string `json:"secondary_types"`
	IsDefault      bool     `json:"is_default"`
	FollowCount    int64    `json:"follow_count"`
}

// releaseProfilesResponse also carries MusicBrainz's types, so the editor
// offers exactly what a profile may hold.
type releaseProfilesResponse struct {
	Profiles       []releaseProfileView `json:"profiles"`
	PrimaryTypes   []string             `json:"primary_types"`
	SecondaryTypes []string             `json:"secondary_types"`
}

// handleListReleaseProfiles implements GET /api/admin/release-profiles.
func (h *handlers) handleListReleaseProfiles(w http.ResponseWriter, r *http.Request) {
	rows, err := dbq.New(h.pool).ListReleaseTypeProfiles(r.Context())
	if err != nil {
		writeErrWithLog(w, h.logger, "admin release profiles: list", apierror.Internal(err))
		return
	}
	out := releaseProfilesResponse{
		Profiles:     make([]releaseProfileView, 0, len(rows)),
		PrimaryTypes: wanted.PrimaryTypes, SecondaryTypes: wanted.SecondaryTypes,
	}
	for _, p := range rows {
		out.Profiles = append(out.Profiles, releaseProfileView{
			ID: uuidToString(p.ID), Name: p.Name, PrimaryTypes: p.PrimaryTypes,
			SecondaryTypes: p.SecondaryTypes, IsDefault: p.IsDefault, FollowCount: p.FollowCount,
		})
	}
	writeJSON(w, http.StatusOK, out)
}

type releaseProfileBody struct {
	Name           string   `json:"name"`
	PrimaryTypes   []string `json:"primary_types"`
	SecondaryTypes []string `json:"secondary_types"`
	IsDefault      bool     `json:"is_default"`
}

func (b releaseProfileBody) input() wanted.ProfileInput {
	return wanted.ProfileInput{
		Name: b.Name, PrimaryTypes: b.PrimaryTypes, SecondaryTypes: b.SecondaryTypes, IsDefault: b.IsDefault,
	}
}

// handleCreateReleaseProfile implements POST /api/admin/release-profiles.
func (h *handlers) handleCreateReleaseProfile(w http.ResponseWriter, r *http.Request) {
	var body releaseProfileBody
	if !decodeBody(w, r, &body) {
		return
	}
	p, err := h.wanted.CreateProfile(r.Context(), body.input())
	if err != nil {
		h.writeProfileErr(w, err)
		return
	}
	writeJSON(w, http.StatusCreated, releaseProfileView{
		ID: uuidToString(p.ID), Name: p.Name, PrimaryTypes: p.PrimaryTypes,
		SecondaryTypes: p.SecondaryTypes, IsDefault: p.IsDefault,
	})
}

// handleUpdateReleaseProfile implements PUT /api/admin/release-profiles/{id}.
// A follow on the profile judges new releases by the new types from its next
// check; releases it has already judged are not judged again.
func (h *handlers) handleUpdateReleaseProfile(w http.ResponseWriter, r *http.Request) {
	id, ok := requireURLUUID(w, r, "id")
	if !ok {
		return
	}
	var body releaseProfileBody
	if !decodeBody(w, r, &body) {
		return
	}
	p, err := h.wanted.UpdateProfile(r.Context(), id, body.input())
	if err != nil {
		h.writeProfileErr(w, err)
		return
	}
	writeJSON(w, http.StatusOK, releaseProfileView{
		ID: uuidToString(p.ID), Name: p.Name, PrimaryTypes: p.PrimaryTypes,
		SecondaryTypes: p.SecondaryTypes, IsDefault: p.IsDefault,
	})
}

// handleDeleteReleaseProfile implements DELETE /api/admin/release-profiles/{id}.
func (h *handlers) handleDeleteReleaseProfile(w http.ResponseWriter, r *http.Request) {
	id, ok := requireURLUUID(w, r, "id")
	if !ok {
		return
	}
	if err := h.wanted.DeleteProfile(r.Context(), id); err != nil {
		h.writeProfileErr(w, err)
		return
	}
	w.WriteHeader(http.StatusNoContent)
}

func (h *handlers) writeProfileErr(w http.ResponseWriter, err error) {
	switch {
	case errors.Is(err, wanted.ErrProfileInvalid):
		writeErr(w, apierror.BadRequest("profile_invalid", err.Error()))
	case errors.Is(err, wanted.ErrProfileNotFound):
		writeErr(w, apierror.NotFound("profile"))
	case errors.Is(err, wanted.ErrProfileNameUsed):
		writeErr(w, apierror.Conflict("profile_name_taken", "a profile already has that name"))
	case errors.Is(err, wanted.ErrProfileInUse):
		writeErr(w, apierror.Conflict("profile_in_use", "artists are followed on this profile; move them first"))
	case errors.Is(err, wanted.ErrProfileDefault):
		writeErr(w, apierror.Conflict("profile_is_default", "the default profile can't be deleted"))
	default:
		writeErrWithLog(w, h.logger, "admin release profiles", apierror.Internal(err))
	}
}