// Package acquire turns the operator's configured indexers and download
// clients into working clients (M502 #5518). Ported from Fabled Librarian's
// internal/acquire.
//
// ONE BUILDER PER KIND. SourceFor makes a search source from a row and
// DownloadClient makes a download client, path mapping included. The grab,
// the importer, the stall watchdog and the settings page's Test all build
// through them, so a Test that passes vouches for the path real traffic takes.
// Clients are rebuilt from the row on every use, so a changed address or a new
// key takes effect on the next call.
package acquire

import (
	"context"
	"time"

	"github.com/jackc/pgx/v5/pgxpool"

	"git.fabledsword.com/bvandeusen/minstrel/internal/db/dbq"
	"git.fabledsword.com/bvandeusen/minstrel/internal/downloader"
	"git.fabledsword.com/bvandeusen/minstrel/internal/exchange"
	"git.fabledsword.com/bvandeusen/minstrel/internal/indexer"
	"git.fabledsword.com/bvandeusen/minstrel/internal/prowlarr"
)

// Kinds: which list a row appears in.
const (
	KindSearch   = "search"
	KindDownload = "download"
)

// Jobs a row can do. An exchange row does each its switch allows; every
// other row does the one its kind names.
const (
	JobSearch     = "search"
	JobDownload   = "download"
	JobEnrichment = "enrichment"
)

// Protocols: which client a row builds.
const (
	ProtocolProwlarr    = "prowlarr"
	ProtocolTorznab     = "torznab"
	ProtocolQBittorrent = "qbittorrent"
	ProtocolExchange    = "exchange"
)

// DefaultCategory files everything Minstrel adds to a download client.
const DefaultCategory = "minstrel"

// addable is what a new row of a protocol starts as.
type addable struct {
	kind      string
	label     string
	category  string
	timeoutMs int32
	perHour   int32
}

// catalogue is every protocol the operator can add. Exchange starts unpaced
// (it searches its own database); the others at 120 searches an hour, which
// keeps a Prowlarr's indexers under the rate most trackers allow.
var catalogue = map[string]addable{
	ProtocolProwlarr:    {kind: KindSearch, label: "Prowlarr", timeoutMs: 60000, perHour: 120},
	ProtocolTorznab:     {kind: KindSearch, label: "Torznab feed", timeoutMs: 30000, perHour: 120},
	ProtocolQBittorrent: {kind: KindDownload, label: "qBittorrent", category: DefaultCategory, timeoutMs: 15000, perHour: 0},
	ProtocolExchange:    {kind: KindDownload, label: "FabledExchange", category: DefaultCategory, timeoutMs: 30000, perHour: 0},
}

// Addable says whether protocol is one the operator can add.
func Addable(protocol string) bool {
	_, ok := catalogue[protocol]
	return ok
}

// Searches says whether a row is a search source.
func Searches(row dbq.AcquisitionService) bool {
	if row.Protocol == ProtocolExchange {
		return row.ServesSearch
	}
	return row.Kind == KindSearch
}

// Fetches says whether a row is a download client.
func Fetches(row dbq.AcquisitionService) bool {
	if row.Protocol == ProtocolExchange {
		return row.ServesDownloads
	}
	return row.Kind == KindDownload
}

// Searcher is a search source.
type Searcher interface {
	Search(ctx context.Context, q indexer.Query) ([]indexer.Result, error)
}

// Fetcher fetches a result's .torrent through the source that offered it.
type Fetcher interface {
	Download(ctx context.Context, r indexer.Result) ([]byte, error)
}

// Source is one configured search source.
type Source struct {
	Code  string
	Label string
	// PerHour is the most searches the schedule sends it an hour; 0 = unpaced.
	PerHour int
	Search  Searcher
	// Fetch is nil for a source whose results are all magnets.
	Fetch Fetcher
}

// SourceFor builds the search source a row describes.
func SourceFor(row dbq.AcquisitionService) Source {
	src := Source{Code: row.Code, Label: row.Label, PerHour: int(row.SearchesPerHour)}
	timeout := msDuration(row.TimeoutMs)
	switch row.Protocol {
	case ProtocolProwlarr:
		c := &prowlarr.Client{Config: prowlarr.Config{
			Code: row.Code, BaseURL: row.BaseUrl, APIKey: row.ApiKey, Timeout: timeout,
		}}
		src.Search, src.Fetch = c, c
	case ProtocolExchange:
		src.Search = ExchangeFor(row)
	default:
		c := &indexer.Torznab{Config: indexer.TorznabConfig{
			Code: row.Code, FeedURL: row.BaseUrl, APIKey: row.ApiKey, Timeout: timeout,
		}}
		src.Search, src.Fetch = c, c
	}
	return src
}

// ExchangeFor builds the search and enrichment client for an exchange row.
func ExchangeFor(row dbq.AcquisitionService) *exchange.Client {
	return &exchange.Client{
		Code: row.Code,
		Config: exchange.Config{
			BaseURL: row.BaseUrl, APIKey: row.ApiKey, Timeout: msDuration(row.TimeoutMs),
		},
	}
}

// DownloadClient builds the download client a row describes, wrapped in its
// path mapping.
func DownloadClient(row dbq.AcquisitionService) (downloader.Driver, error) {
	d, err := downloader.For(row.Protocol, downloader.Config{
		BaseURL: row.BaseUrl, Username: row.Username, Password: row.Password,
		APIKey: row.ApiKey, Category: row.Category, Timeout: msDuration(row.TimeoutMs),
	})
	if err != nil {
		return nil, err
	}
	return downloader.Mapped(d, downloader.PathMap{Local: row.LocalPath, Remote: row.RemotePath}), nil
}

// Sources builds every enabled search source.
func Sources(ctx context.Context, pool *pgxpool.Pool) ([]Source, error) {
	rows, err := dbq.New(pool).ListUsableAcquisitionServices(ctx, JobSearch)
	if err != nil {
		return nil, err
	}
	out := make([]Source, len(rows))
	for i, r := range rows {
		out[i] = SourceFor(r)
	}
	return out, nil
}

func msDuration(ms int32) time.Duration { return time.Duration(ms) * time.Millisecond }