// tofuproxy -- flexible HTTP/HTTPS proxy, TLS terminator, X.509 TOFU
//              manager, WARC/geminispace browser
// Copyright (C) 2021-2024 Sergey Matveev <stargrave@stargrave.org>
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, version 3 of the License.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

package warc

import (
	"io"
	"strings"
)

type Record struct {
	WARCPath string
	Offset   int64
	Size     int64

	Hdr      Header
	HdrLen   int
	HdrLines []string

	Continuations []*Record
}

func (rec *Record) URI() string {
	return strings.Trim(rec.Hdr.Get("WARC-Target-URI"), "<>")
}

func (rec *Record) TotalSize() int64 {
	s := rec.Size
	for _, r := range rec.Continuations {
		s += r.Size
	}
	return s
}

type SelfRecordReader struct {
	lr  *io.LimitedReader
	rrr io.ReadCloser
}

func (srr *SelfRecordReader) Read(p []byte) (n int, err error) {
	n, err = srr.lr.Read(p)
	if err != nil {
		srr.Close()
	}
	return
}

func (srr *SelfRecordReader) Close() error {
	return srr.rrr.Close()
}

func (rec *Record) selfReader(noHdr bool, offsets []Offset) (*SelfRecordReader, error) {
	offset := rec.Offset
	if noHdr {
		offset += int64(rec.HdrLen)
	}
	rrr, err := Open(rec.WARCPath, offsets, offset)
	if err != nil {
		return nil, err
	}
	size := rec.Size
	if !noHdr {
		size += int64(rec.HdrLen)
	}
	return &SelfRecordReader{lr: &io.LimitedReader{R: rrr, N: size}, rrr: rrr}, nil
}

type RecordReader struct {
	r    io.Reader
	srrs []*SelfRecordReader
}

func (rec *Record) Reader(
	noHdr bool,
	warcOffsets map[string][]Offset,
) (*RecordReader, error) {
	srrs := make([]*SelfRecordReader, 0, 1+len(rec.Continuations))
	rs := make([]io.Reader, 0, 1+len(rec.Continuations))
	for i, r := range append([]*Record{rec}, rec.Continuations...) {
		if i > 0 {
			noHdr = true
		}
		srr, err := r.selfReader(noHdr, warcOffsets[rec.WARCPath])
		if err != nil {
			for _, srr := range srrs {
				srr.Close()
			}
			return nil, err
		}
		srrs = append(srrs, srr)
		rs = append(rs, srr)
	}
	return &RecordReader{r: io.MultiReader(rs...), srrs: srrs}, nil
}

func (rr *RecordReader) Read(p []byte) (n int, err error) {
	n, err = rr.r.Read(p)
	if err != nil {
		rr.Close()
	}
	return
}

func (rr *RecordReader) Close() error {
	for _, srr := range rr.srrs {
		srr.Close()
	}
	return nil
}