package bible

import (
	"os"
	"path/filepath"
	"sort"
	"strings"
	"sync"
)

var (
	regMu      sync.Mutex
	userDir    string
	regBuilt   bool
	regMeta    map[string]CorpusMeta // code -> meta (user overrides embed)
	regUserTSV map[string]string     // code -> user .tsv path (override source)
)

// SetUserCorporaDir sets the drop-in dir and invalidates the registry cache.
// Empty string disables user corpora (used by tests).
func SetUserCorporaDir(dir string) {
	regMu.Lock()
	userDir = dir
	regBuilt = false
	regMu.Unlock()

	corporaMu.Lock()
	corpora = map[string]*corpus{} // drop cached loads so overrides take effect
	corporaMu.Unlock()
}

func buildRegistry() {
	if regBuilt {
		return
	}
	regMeta = map[string]CorpusMeta{}
	regUserTSV = map[string]string{}
	// embedded first (core FS = vul always; optional FS = rest under -tags fullbible)
	for _, name := range embCorpusFiles() {
		if code, ok := strings.CutSuffix(name, ".ini"); ok {
			if m, ok := embeddedCorpusMeta(code); ok {
				regMeta[code] = m
			}
		}
	}
	// user dir overrides
	if userDir != "" {
		ents, _ := os.ReadDir(userDir)
		for _, e := range ents {
			name := e.Name()
			if code, ok := strings.CutSuffix(name, ".tsv"); ok {
				regUserTSV[code] = filepath.Join(userDir, name)
				if _, have := regMeta[code]; !have {
					regMeta[code] = CorpusMeta{Code: code, PsalmSystem: "vulgate", Autoselect: true}
				}
			}
		}
		for _, e := range ents {
			if code, ok := strings.CutSuffix(e.Name(), ".ini"); ok {
				data, err := os.ReadFile(filepath.Join(userDir, e.Name()))
				if err == nil {
					regMeta[code] = parseCorpusMeta(code, data)
				}
			}
		}
	}
	regBuilt = true
}

// Corpora returns all known corpora, sorted by code.
func Corpora() []CorpusMeta {
	regMu.Lock()
	defer regMu.Unlock()
	buildRegistry()
	out := make([]CorpusMeta, 0, len(regMeta))
	for _, m := range regMeta {
		out = append(out, m)
	}
	sort.Slice(out, func(i, j int) bool { return out[i].Code < out[j].Code })
	return out
}

// Meta returns a corpus's metadata.
func Meta(code string) (CorpusMeta, bool) {
	regMu.Lock()
	defer regMu.Unlock()
	buildRegistry()
	m, ok := regMeta[code]
	return m, ok
}

// CorporaForLang returns corpora whose lang == lang, sorted by code.
func CorporaForLang(lang string) []CorpusMeta {
	var out []CorpusMeta
	for _, m := range Corpora() {
		if m.Lang == lang {
			out = append(out, m)
		}
	}
	return out
}

// userTSVPath returns the override .tsv path for code, or "".
func userTSVPath(code string) string {
	regMu.Lock()
	defer regMu.Unlock()
	buildRegistry()
	return regUserTSV[code]
}