package api

import (
	"context"
	"encoding/json"
	"errors"
	"net/http"
	"slices"
	"time"

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

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

// Searching for wants and grabbing releases (M502 #5521): the schedule's
// settings, each want's candidates, and a person's Search, Grab and "never
// this one".

// searchTimeout bounds a search a person waits on: a Prowlarr fanning out to
// many trackers can take most of a minute.
const searchTimeout = 2 * time.Minute

type searchSettingsView struct {
	AutoGrab            bool               `json:"auto_grab"`
	SearchIntervalHours int32              `json:"search_interval_hours"`
	AllowedQualities    []string           `json:"allowed_qualities"`
	Tiers               []release.TierInfo `json:"tiers"`
	LastPassAt          *string            `json:"last_pass_at"`
	LastPass            json.RawMessage    `json:"last_pass"`
	// ImportRoot is the library folder new music is filed into (#5522); ""
	// is the first of ScanPaths, the library's folders.
	ImportRoot string   `json:"import_root"`
	ScanPaths  []string `json:"scan_paths"`
	// The download lifecycle (#5523): seed an imported download to this
	// ratio or for this many days; give up on one nobody shares after this
	// many hours. 0 is: remove once imported, no time limit, never.
	SeedRatio  float32 `json:"seed_ratio"`
	SeedDays   int32   `json:"seed_days"`
	StallHours int32   `json:"stall_hours"`
	// UpgradeUntil is the tier a held album is upgraded to (#5524); "" is
	// no quality upgrades.
	UpgradeUntil string `json:"upgrade_until"`
}

func searchSettings(s dbq.AcquisitionSetting, roots []string) searchSettingsView {
	v := searchSettingsView{
		AutoGrab: s.AutoGrab, SearchIntervalHours: s.SearchIntervalHours,
		AllowedQualities: s.AllowedQualities, Tiers: release.Tiers, LastPass: s.LastPass,
		ImportRoot: s.ImportRoot, ScanPaths: roots,
		SeedRatio: s.SeedRatio, SeedDays: s.SeedDays, StallHours: s.StallHours,
		UpgradeUntil: s.UpgradeUntil,
	}
	if v.ScanPaths == nil {
		v.ScanPaths = []string{}
	}
	if v.AllowedQualities == nil {
		v.AllowedQualities = []string{}
	}
	if len(v.LastPass) == 0 {
		v.LastPass = json.RawMessage("{}")
	}
	if s.LastPassAt.Valid {
		at := formatTimestamp(s.LastPassAt)
		v.LastPassAt = &at
	}
	return v
}

// handleGetSearchSettings implements GET /api/admin/acquisition/settings.
func (h *handlers) handleGetSearchSettings(w http.ResponseWriter, r *http.Request) {
	s, err := dbq.New(h.pool).GetAcquisitionSettings(r.Context())
	if err != nil {
		writeErrWithLog(w, h.logger, "admin search settings: get", apierror.Internal(err))
		return
	}
	writeJSON(w, http.StatusOK, searchSettings(s, h.importer.Roots))
}

type putSearchSettingsBody struct {
	AutoGrab            bool     `json:"auto_grab"`
	SearchIntervalHours int32    `json:"search_interval_hours"`
	AllowedQualities    []string `json:"allowed_qualities"`
	ImportRoot          string   `json:"import_root"`
	SeedRatio           float32  `json:"seed_ratio"`
	SeedDays            int32    `json:"seed_days"`
	StallHours          int32    `json:"stall_hours"`
	UpgradeUntil        string   `json:"upgrade_until"`
}

// handlePutSearchSettings implements PUT /api/admin/acquisition/settings.
func (h *handlers) handlePutSearchSettings(w http.ResponseWriter, r *http.Request) {
	var body putSearchSettingsBody
	if !decodeBody(w, r, &body) {
		return
	}
	if body.SearchIntervalHours < 0 || body.SearchIntervalHours > 720 {
		writeErr(w, apierror.BadRequest("bad_interval", "search_interval_hours must be between 0 and 720"))
		return
	}
	if len(body.AllowedQualities) == 0 {
		writeErr(w, apierror.BadRequest("bad_quality", "allow at least one quality"))
		return
	}
	for _, t := range body.AllowedQualities {
		if !release.KnownTier(t) {
			writeErr(w, apierror.BadRequest("bad_quality", "unknown quality "+t))
			return
		}
	}
	if body.UpgradeUntil != "" && !release.KnownTier(body.UpgradeUntil) {
		writeErr(w, apierror.BadRequest("bad_upgrade_until", "unknown quality "+body.UpgradeUntil))
		return
	}
	if body.ImportRoot != "" && !slices.Contains(h.importer.Roots, body.ImportRoot) {
		writeErr(w, apierror.BadRequest("bad_import_root", "file new music into one of the library's folders"))
		return
	}
	if body.SeedRatio < 0 || body.SeedRatio > 100 || body.SeedDays < 0 || body.SeedDays > 365 ||
		body.StallHours < 0 || body.StallHours > 720 {
		writeErr(w, apierror.BadRequest("bad_lifecycle",
			"seed ratio must be 0 to 100, seed days 0 to 365 and stall hours 0 to 720"))
		return
	}
	s, err := dbq.New(h.pool).UpdateAcquisitionSettings(r.Context(), dbq.UpdateAcquisitionSettingsParams{
		AutoGrab: body.AutoGrab, SearchIntervalHours: body.SearchIntervalHours, AllowedQualities: body.AllowedQualities,
		ImportRoot: body.ImportRoot, SeedRatio: body.SeedRatio, SeedDays: body.SeedDays, StallHours: body.StallHours,
		UpgradeUntil: body.UpgradeUntil,
	})
	if err != nil {
		writeErrWithLog(w, h.logger, "admin search settings: put", apierror.Internal(err))
		return
	}
	writeJSON(w, http.StatusOK, searchSettings(s, h.importer.Roots))
}

// candidateView is one release a want's last search found.
type candidateView struct {
	Key         string          `json:"key"`
	Name        string          `json:"name"`
	InfoHash    string          `json:"info_hash"`
	Indexer     string          `json:"indexer"`
	SizeBytes   int64           `json:"size_bytes"`
	Seeders     int32           `json:"seeders"`
	FilesCount  int32           `json:"files_count"`
	Format      string          `json:"format"`
	Quality     string          `json:"quality"`
	Year        int32           `json:"year"`
	Verdict     string          `json:"verdict"`
	Reason      string          `json:"reason"`
	Reasons     json.RawMessage `json:"reasons"`
	FoldedFrom  []string        `json:"folded_from"`
	SearchedAt  string          `json:"searched_at"`
	Downloading bool            `json:"downloading"`
}

// handleListCandidates implements GET /api/admin/wanted/{id}/candidates.
func (h *handlers) handleListCandidates(w http.ResponseWriter, r *http.Request) {
	id, ok := requireURLUUID(w, r, "id")
	if !ok {
		return
	}
	q := dbq.New(h.pool)
	rows, err := q.ListWantCandidates(r.Context(), id)
	if err != nil {
		writeErrWithLog(w, h.logger, "admin wanted: candidates", apierror.Internal(err))
		return
	}
	live, err := q.GetLiveGrab(r.Context(), id)
	if err != nil && !errors.Is(err, pgx.ErrNoRows) {
		writeErrWithLog(w, h.logger, "admin wanted: live grab", apierror.Internal(err))
		return
	}
	out := make([]candidateView, 0, len(rows))
	for _, c := range rows {
		v := candidateView{
			Key: c.Key, Name: c.Name, InfoHash: c.InfoHash, Indexer: c.Indexer, SizeBytes: c.SizeBytes,
			Seeders: c.Seeders, FilesCount: c.FilesCount, Format: c.Format, Quality: c.Quality, Year: c.Year,
			Verdict: c.Verdict, Reason: c.Reason, Reasons: c.Reasons, FoldedFrom: c.FoldedFrom,
			SearchedAt:  formatTimestamp(c.SearchedAt),
			Downloading: live.ID.Valid && live.Key == c.Key,
		}
		if v.FoldedFrom == nil {
			v.FoldedFrom = []string{}
		}
		if len(v.Reasons) == 0 {
			v.Reasons = json.RawMessage("[]")
		}
		out = append(out, v)
	}
	writeJSON(w, http.StatusOK, map[string]any{"items": out})
}

// handleSearchWant implements POST /api/admin/wanted/{id}/search: search
// now, as the schedule would, taking the best release when auto-grab is on.
func (h *handlers) handleSearchWant(w http.ResponseWriter, r *http.Request) {
	id, ok := requireURLUUID(w, r, "id")
	if !ok {
		return
	}
	ctx, cancel := context.WithTimeout(r.Context(), searchTimeout)
	defer cancel()
	res, err := h.searcher.SearchNow(ctx, id)
	if h.writeSearchErr(w, err) {
		return
	}
	writeJSON(w, http.StatusOK, res)
}

type grabBody struct {
	Key   string `json:"key"`
	Force bool   `json:"force"`
}

// grabView is what came of a person's grab.
type grabView struct {
	Added        bool   `json:"added"`
	Refused      bool   `json:"refused"`
	Gone         bool   `json:"gone"`
	Unconfigured bool   `json:"unconfigured"`
	Missing      string `json:"missing,omitempty"`
	Kept         bool   `json:"kept"`
	Replaced     bool   `json:"replaced"`
	Verdict      string `json:"verdict,omitempty"`
	Reason       string `json:"reason,omitempty"`
	Error        string `json:"error,omitempty"`
}

// handleGrabCandidate implements POST /api/admin/wanted/{id}/grab: take the
// release named by key. The search runs again first, so the indexer's link
// never leaves the server; force takes what the verdict would not.
func (h *handlers) handleGrabCandidate(w http.ResponseWriter, r *http.Request) {
	admin, ok := requireUser(w, r)
	if !ok {
		return
	}
	id, ok := requireURLUUID(w, r, "id")
	if !ok {
		return
	}
	var body grabBody
	if !decodeBody(w, r, &body) {
		return
	}
	ctx, cancel := context.WithTimeout(r.Context(), searchTimeout)
	defer cancel()
	took, err := h.searcher.Take(ctx, id, body.Key, body.Force, admin.ID)
	if h.writeSearchErr(w, err) {
		return
	}
	v := grabView{
		Added: took.Added, Refused: took.Refused, Gone: took.Gone, Unconfigured: took.Unconfigured,
		Missing: took.Missing, Error: took.Error,
	}
	if took.Chosen != nil {
		v.Verdict, v.Reason = string(took.Chosen.Verdict), took.Chosen.Reason
	}
	if took.Contest != nil {
		v.Kept, v.Replaced = took.Contest.Kept, took.Contest.Replaced
		if took.Contest.Kept {
			v.Reason = took.Contest.Reason
		}
	}
	writeJSON(w, http.StatusOK, v)
}

type blockBody struct {
	Key string `json:"key"`
}

// handleBlockCandidate implements POST /api/admin/wanted/{id}/block: never
// take this release again, for any want.
func (h *handlers) handleBlockCandidate(w http.ResponseWriter, r *http.Request) {
	admin, ok := requireUser(w, r)
	if !ok {
		return
	}
	id, ok := requireURLUUID(w, r, "id")
	if !ok {
		return
	}
	var body blockBody
	if !decodeBody(w, r, &body) {
		return
	}
	c, err := dbq.New(h.pool).GetWantCandidate(r.Context(), dbq.GetWantCandidateParams{WantID: id, Key: body.Key})
	if errors.Is(err, pgx.ErrNoRows) {
		writeErr(w, apierror.NotFound("candidate"))
		return
	}
	if err != nil {
		writeErrWithLog(w, h.logger, "admin wanted: block", apierror.Internal(err))
		return
	}
	if c.InfoHash == "" {
		writeErr(w, apierror.BadRequest("no_infohash", "this release has no infohash to set aside by"))
		return
	}
	if err := acquire.NewMemory(h.pool).Block(r.Context(), dbq.BlockReleaseParams{
		InfoHash: c.InfoHash, Name: c.Name, Reason: acquire.BlockOperator, WantID: id, BlockedBy: admin.ID,
	}); err != nil {
		writeErrWithLog(w, h.logger, "admin wanted: block", apierror.Internal(err))
		return
	}
	w.WriteHeader(http.StatusNoContent)
}

// handleUnblockRelease implements DELETE /api/admin/release-blocks/{hash}.
func (h *handlers) handleUnblockRelease(w http.ResponseWriter, r *http.Request) {
	removed, err := acquire.NewMemory(h.pool).Unblock(r.Context(), chi.URLParam(r, "hash"))
	if err != nil {
		writeErrWithLog(w, h.logger, "admin wanted: unblock", apierror.Internal(err))
		return
	}
	if !removed {
		writeErr(w, apierror.NotFound("block"))
		return
	}
	w.WriteHeader(http.StatusNoContent)
}

// writeSearchErr answers a Searcher error, and says whether there was one.
func (h *handlers) writeSearchErr(w http.ResponseWriter, err error) bool {
	switch {
	case err == nil:
		return false
	case errors.Is(err, pgx.ErrNoRows):
		writeErr(w, apierror.NotFound("want"))
	case errors.Is(err, wanted.ErrWantHeld):
		writeErr(w, apierror.Conflict("want_held", "the library already holds this album, and it isn't wanted for a better copy"))
	default:
		writeErrWithLog(w, h.logger, "admin wanted: search", apierror.Internal(err))
	}
	return true
}