package kjv

import (
	"crypto/subtle"
	"database/sql"
	"encoding/json"
	"io"
	"net"
	"net/http"
	"strings"
	"time"
)

// Optional endpoints backed by the separate sermon database (KJV_SERMON_DB)
// and the separate semantic search service (KJV_SEMANTIC_ADDR, default
// localhost:1613). Neither is part of the distribution; without them these
// endpoints answer with an error.

func rowsToMaps(rows *sql.Rows) ([]map[string]any, error) {
	defer rows.Close()
	cols, err := rows.Columns()
	if err != nil {
		return nil, err
	}
	out := []map[string]any{}
	for rows.Next() {
		vals := make([]any, len(cols))
		ptrs := make([]any, len(cols))
		for i := range vals {
			ptrs[i] = &vals[i]
		}
		if err := rows.Scan(ptrs...); err != nil {
			return nil, err
		}
		m := map[string]any{}
		for i, c := range cols {
			if b, ok := vals[i].([]byte); ok {
				vals[i] = string(b)
			}
			m[c] = vals[i]
		}
		out = append(out, m)
	}
	return out, rows.Err()
}

func (a *App) sermonQuery(query string, args ...any) Resp {
	if a.sermonDB == nil {
		return jsonStatus(map[string]string{"error": "Sermon database not found"}, http.StatusServiceUnavailable)
	}
	rows, err := a.sermonDB.Query(query, args...)
	if err != nil {
		lg.Error("sermon query: %v", err)
		return errJSON(http.StatusInternalServerError, "Sermon database error")
	}
	out, err := rowsToMaps(rows)
	if err != nil {
		return errJSON(http.StatusInternalServerError, "Sermon database error")
	}
	return jsonR(out)
}

const sermonCols = "select distinct title,url,denomination,preacher,church_name from verse_refs where "

// handleSermons serves everything under /sermon/ and /sermons/ ... by hand,
// since the paths overlap in ways the router would reject.
func (a *App) handleSermons(path string) Resp {
	parts := strings.Split(strings.Trim(path, "/"), "/")
	switch {
	case len(parts) == 1 && parts[0] == "sermons":
		return a.sermonQuery("select distinct title,url,denomination,preacher,church_name,filename from verse_refs")
	case len(parts) == 3 && parts[0] == "sermons" && parts[1] == "preacher":
		return a.sermonQuery(sermonCols+"preacher=?", parts[2])
	case len(parts) == 3 && parts[0] == "sermons" && parts[1] == "church":
		return a.sermonQuery(sermonCols+"church_name=?", parts[2])
	case len(parts) == 3 && parts[0] == "sermons" && parts[1] == "denomination":
		return a.sermonQuery(sermonCols+"denomination=?", parts[2])
	case len(parts) == 3 && parts[0] == "sermon" && parts[1] == "search":
		return a.sermonsByRef(parts[2])
	case len(parts) == 3 && parts[0] == "sermon" && parts[1] == "url":
		return a.sermonQuery(sermonCols+"url=?", parts[2])
	case len(parts) == 3 && parts[0] == "sermon" && parts[2] == "verses":
		return a.sermonQuery("select distinct verse_id,text from verse_refs where filename=?", parts[1])
	case len(parts) == 2 && parts[0] == "sermon":
		return a.sermonQuery(sermonCols+"filename=?", parts[1])
	}
	return a.notFound()
}

func (a *App) sermonsByRef(ref string) Resp {
	id, ok := a.refVerseID(ref)
	if !ok {
		return a.notFound()
	}
	if a.sermonDB == nil {
		return jsonR(map[string]string{"error": "Sermon database not found"})
	}
	rows, err := a.sermonDB.Query("select * from verse_refs where verse_id=?", id)
	if err != nil {
		return errJSON(http.StatusInternalServerError, "Sermon database error")
	}
	out, err := rowsToMaps(rows)
	if err != nil {
		return errJSON(http.StatusInternalServerError, "Sermon database error")
	}
	for _, m := range out {
		if vid, ok := m["verse_id"].(int64); ok {
			if v := a.store.Range(vid, 0); len(v) == 1 {
				m["kjv"] = v[0].Text
			}
		}
	}
	return jsonR(out)
}

// refVerseID: the verse id of the first reference in "1John5:7" style text.
func (a *App) refVerseID(ref string) (int64, bool) {
	resolved := a.res.Resolve(ref, true)
	if resolved == nil {
		return 0, false
	}
	return resolved.Refs[0].Start, true
}

func (a *App) handleRef(ref string) Resp {
	id, ok := a.refVerseID(ref)
	if !ok {
		return a.notFound()
	}
	return htmlR(itoa64(id))
}

func (a *App) handleNaturalPost(body io.Reader) Resp {
	var req struct {
		Token *string `json:"token"`
		Query string  `json:"query"`
	}
	if err := json.NewDecoder(io.LimitReader(body, 1<<16)).Decode(&req); err != nil {
		return errJSON(http.StatusBadRequest, "Invalid request format")
	}
	if req.Token == nil {
		return errJSON(http.StatusUnauthorized, "Missing token in request body")
	}
	if a.secretKey == "" || subtle.ConstantTimeCompare([]byte(*req.Token), []byte(a.secretKey)) != 1 {
		return errJSON(http.StatusUnauthorized, "Invalid Authorization")
	}
	conn, err := net.DialTimeout("tcp", a.semantic, 3*time.Second)
	if err != nil {
		return errJSON(http.StatusBadGateway, "Semantic search is not available")
	}
	defer conn.Close()
	conn.SetDeadline(time.Now().Add(30 * time.Second))
	payload, _ := json.Marshal(map[string]string{"query": req.Query})
	if _, err := conn.Write(payload); err != nil {
		return errJSON(http.StatusBadGateway, "Semantic search is not available")
	}
	data, err := io.ReadAll(io.LimitReader(conn, 8<<20))
	var out any
	if err != nil || json.Unmarshal(data, &out) != nil {
		return errJSON(http.StatusBadGateway, "Semantic search gave an invalid answer")
	}
	return jsonR(out)
}