//go:build xapian

package index

/*
#cgo pkg-config: xapian-core
#cgo LDFLAGS: -lstdc++
#include "xapian_wrapper.h"
#include <stdlib.h>
*/
import "C"
import (
	"encoding/json"
	"fmt"
	"unsafe"
)

type xapianIndex struct {
	db *C.XapianDB
}

func newXapian(dir string) (Indexer, error) {
	cdir := C.CString(dir)
	defer C.free(unsafe.Pointer(cdir))
	var cerr *C.char
	db := C.xapian_open(cdir, 1, &cerr)
	if db == nil {
		msg := C.GoString(cerr)
		C.xapian_free_string(cerr)
		return nil, fmt.Errorf("xapian open: %s", msg)
	}
	return &xapianIndex{db: db}, nil
}

func (x *xapianIndex) IndexSync(doc MailDocument) error {
	cid := C.CString(doc.ID)
	defer C.free(unsafe.Pointer(cid))
	cfrom := C.CString(doc.From)
	defer C.free(unsafe.Pointer(cfrom))
	cto := C.CString(doc.To)
	defer C.free(unsafe.Pointer(cto))
	csubj := C.CString(doc.Subject)
	defer C.free(unsafe.Pointer(csubj))
	cbody := C.CString(doc.Body)
	defer C.free(unsafe.Pointer(cbody))
	hasAttach := C.int(0)
	if doc.HasAttachment {
		hasAttach = C.int(1)
	}
	var cerr *C.char
	rc := C.xapian_index(x.db, cid, cfrom, cto, csubj, cbody, C.longlong(doc.Date.Unix()), hasAttach, &cerr)
	if rc != 0 {
		msg := C.GoString(cerr)
		C.xapian_free_string(cerr)
		return fmt.Errorf("xapian index: %s", msg)
	}
	return nil
}

func (x *xapianIndex) Delete(id string) error {
	cid := C.CString(id)
	defer C.free(unsafe.Pointer(cid))
	var cerr *C.char
	rc := C.xapian_delete(x.db, cid, &cerr)
	if rc != 0 {
		msg := C.GoString(cerr)
		C.xapian_free_string(cerr)
		return fmt.Errorf("xapian delete: %s", msg)
	}
	return nil
}

func (x *xapianIndex) Search(req SearchRequest) (*SearchResult, error) {
	cquery := C.CString(req.Query)
	defer C.free(unsafe.Pointer(cquery))
	cfrom := C.CString(req.From)
	defer C.free(unsafe.Pointer(cfrom))
	cown := C.CString(req.OwnEmail)
	defer C.free(unsafe.Pointer(cown))
	cto := C.CString(req.To)
	defer C.free(unsafe.Pointer(cto))

	var dateFrom, dateTo C.longlong
	if req.DateFrom != nil {
		dateFrom = C.longlong(req.DateFrom.Unix())
	}
	if req.DateTo != nil {
		dateTo = C.longlong(req.DateTo.Unix())
	}
	page := req.Page
	if page < 1 {
		page = 1
	}
	offset := C.int((page - 1) * req.PageSize)
	limit := C.int(req.PageSize)
	if limit <= 0 {
		limit = 25
	}

	// Sort mode: 0=relevance, 1=date_desc (default), 2=date_asc
	sortMode := C.int(1)
	switch req.Sort {
	case "relevance":
		sortMode = C.int(0)
	case "date_asc":
		sortMode = C.int(2)
	}

	// Attachment filter: 0=all, 1=only with, -1=only without
	attachFilter := C.int(0)
	if req.HasAttachment != nil {
		if *req.HasAttachment {
			attachFilter = C.int(1)
		} else {
			attachFilter = C.int(-1)
		}
	}

	var cerr *C.char
	cresult := C.xapian_search(x.db, cquery, cfrom, cown, cto, dateFrom, dateTo, offset, limit, sortMode, attachFilter, &cerr)
	if cresult == nil {
		msg := C.GoString(cerr)
		C.xapian_free_string(cerr)
		return nil, fmt.Errorf("xapian search: %s", msg)
	}
	defer C.xapian_free_string(cresult)
	jsonStr := C.GoString(cresult)

	var raw struct {
		Total int `json:"total"`
		Hits  []struct {
			ID    string  `json:"id"`
			Score float64 `json:"score"`
		} `json:"hits"`
	}
	if err := json.Unmarshal([]byte(jsonStr), &raw); err != nil {
		return nil, fmt.Errorf("xapian parse result: %w", err)
	}
	hits := make([]Hit, len(raw.Hits))
	for i, h := range raw.Hits {
		hits[i] = Hit{ID: h.ID, Score: h.Score}
	}
	return &SearchResult{Total: raw.Total, Hits: hits}, nil
}

func (x *xapianIndex) Close() error {
	C.xapian_close(x.db)
	return nil
}