package interp

import (
	"bytes"
	"context"
	"crypto/aes"
	"crypto/cipher"
	"crypto/md5"
	"encoding/base64"
	"encoding/hex"
	"encoding/json"
	"errors"
	"fmt"
	"fq/format"
	"fq/format/registry"
	"fq/internal/aheadreadseeker"
	"fq/internal/ctxreadseeker"
	"fq/internal/ioextra"
	"fq/internal/progressreadseeker"
	"fq/pkg/bitio"
	"fq/pkg/decode"
	"hash"
	"io"
	"io/fs"
	"io/ioutil"
	"log"
	"math/big"
	"net/url"
	"strings"
	"time"

	"github.com/itchyny/gojq"
)

// TODO: make it nicer somehow? generate generators? remove from struct?
func (i *Interp) makeFunctions(registry *registry.Registry) []Function {
	fs := []Function{
		{[]string{"tty"}, 0, 0, i.tty, nil},

		{[]string{"readline"}, 0, 2, i.readline, nil},
		{[]string{"eval"}, 1, 2, nil, i.eval},
		{[]string{"print"}, 0, 0, nil, i.print},
		{[]string{"println"}, 0, 0, nil, i.println},
		{[]string{"stderr"}, 0, 0, nil, i.stderr},
		{[]string{"debug"}, 0, 0, i.debug, nil},

		{[]string{"_complete_query"}, 0, 0, i._completeQuery, nil},
		{[]string{"_display_name"}, 0, 0, i._displayName, nil},
		{[]string{"_extkeys"}, 0, 0, i._extKeys, nil},
		{[]string{"_global_state"}, 0, 1, i.makeStateFn(i.state), nil},

		{[]string{"formats"}, 0, 0, i.formats, nil},
		{[]string{"history"}, 0, 0, i.history, nil},

		{[]string{"open"}, 0, 0, i._open, nil},
		{[]string{"decode"}, 0, 1, i.makeDecodeFn(registry, registry.MustGroup(format.PROBE)), nil},

		{[]string{"display", "d"}, 0, 1, nil, i.makeDisplayFn(nil)},
		{[]string{"verbose", "v"}, 0, 1, nil, i.makeDisplayFn(map[string]interface{}{"verbose": true})},
		{[]string{"preview", "p"}, 0, 1, nil, i.preview},
		{[]string{"hexdump", "hd", "h"}, 0, 1, nil, i.hexdump},

		{[]string{"string"}, 0, 0, i.string_, nil},
		{[]string{"bytes"}, 0, 0, i.bytes, nil},
		{[]string{"bits"}, 0, 0, i.bits, nil},
		{[]string{"tovalue"}, 0, 0, i.tovalue, nil},

		{[]string{"hex"}, 0, 0, makeStringBitBufTransformFn(
			func(r io.Reader) (io.Reader, error) { return hex.NewDecoder(r), nil },
			func(r io.Writer) (io.Writer, error) { return hex.NewEncoder(r), nil },
		), nil},

		{[]string{"base64"}, 0, 0, makeStringBitBufTransformFn(
			func(r io.Reader) (io.Reader, error) { return base64.NewDecoder(base64.StdEncoding, r), nil },
			func(r io.Writer) (io.Writer, error) { return base64.NewEncoder(base64.StdEncoding, r), nil },
		), nil},
		{[]string{"rawbase64"}, 0, 0, makeStringBitBufTransformFn(
			func(r io.Reader) (io.Reader, error) { return base64.NewDecoder(base64.RawURLEncoding, r), nil },
			func(r io.Writer) (io.Writer, error) { return base64.NewEncoder(base64.RawURLEncoding, r), nil },
		), nil},

		{[]string{"urlbase64"}, 0, 0, makeStringBitBufTransformFn(
			func(r io.Reader) (io.Reader, error) { return base64.NewDecoder(base64.URLEncoding, r), nil },
			func(r io.Writer) (io.Writer, error) { return base64.NewEncoder(base64.URLEncoding, r), nil },
		), nil},

		{[]string{"nal_unescape"}, 0, 0, makeBitBufTransformFn(func(r io.Reader) (io.Reader, error) {
			return &decode.NALUnescapeReader{Reader: r}, nil
		}), nil},

		{[]string{"md5"}, 0, 0, makeHashFn(func() (hash.Hash, error) { return md5.New(), nil }), nil},

		{[]string{"query_escape"}, 0, 0, i.queryEscape, nil},
		{[]string{"query_unescape"}, 0, 0, i.queryUnescape, nil},
		{[]string{"path_escape"}, 0, 0, i.pathEscape, nil},
		{[]string{"path_unescape"}, 0, 0, i.pathUnescape, nil},
		{[]string{"aes_ctr"}, 1, 2, i.aesCtr, nil},

		{[]string{"find"}, 1, 1, nil, i.find},
	}
	for name, f := range i.registry.Groups {
		fs = append(fs, Function{[]string{name}, 0, 0, i.makeDecodeFn(registry, f), nil})
	}

	return fs
}

func (i *Interp) tty(c interface{}, a []interface{}) interface{} {
	w, h := i.evalContext.stdout.Size()
	return map[string]interface{}{
		"is_terminal": i.evalContext.stdout.IsTerminal(),
		"width":       w,
		"height":      h,
	}
}

// transform byte string <-> buffer using fn:s
func makeStringBitBufTransformFn(
	decodeFn func(r io.Reader) (io.Reader, error),
	encodeFn func(w io.Writer) (io.Writer, error),
) func(c interface{}, a []interface{}) interface{} {
	return func(c interface{}, a []interface{}) interface{} {
		switch c := c.(type) {
		case string:
			bb, err := toBuffer(c)
			if err != nil {
				return err
			}

			r, err := decodeFn(bb)
			if err != nil {
				return err
			}

			buf := &bytes.Buffer{}
			if _, err := io.Copy(buf, r); err != nil {
				return err
			}
			outBB := bitio.NewBufferFromBytes(buf.Bytes(), -1)

			return newBifBufObject(outBB, 8)
		default:
			bb, err := toBuffer(c)
			if err != nil {
				return err
			}

			buf := &bytes.Buffer{}
			w, err := encodeFn(buf)
			if err != nil {
				return err
			}

			if _, err := io.Copy(w, bb); err != nil {
				return err
			}

			if c, ok := w.(io.Closer); ok {
				c.Close()
			}

			return buf.String()
		}
	}
}

// transform to buffer using fn
func makeBitBufTransformFn(fn func(r io.Reader) (io.Reader, error)) func(c interface{}, a []interface{}) interface{} {
	return func(c interface{}, a []interface{}) interface{} {
		inBB, err := toBuffer(c)
		if err != nil {
			return err
		}

		r, err := fn(inBB)
		if err != nil {
			return err
		}

		outBuf := &bytes.Buffer{}
		if _, err := io.Copy(outBuf, r); err != nil {
			return err
		}

		outBB := bitio.NewBufferFromBytes(outBuf.Bytes(), -1)

		return newBifBufObject(outBB, 8)
	}
}

// transform to buffer using fn
func makeHashFn(fn func() (hash.Hash, error)) func(c interface{}, a []interface{}) interface{} {
	return func(c interface{}, a []interface{}) interface{} {
		inBB, err := toBuffer(c)
		if err != nil {
			return err
		}

		h, err := fn()
		if err != nil {
			return err
		}
		if _, err := io.Copy(h, inBB); err != nil {
			return err
		}

		outBB := bitio.NewBufferFromBytes(h.Sum(nil), -1)

		return newBifBufObject(outBB, 8)
	}
}

func (i *Interp) readline(c interface{}, a []interface{}) interface{} {
	var ok bool
	completeFn := ""
	prompt := ""

	if len(a) > 0 {
		prompt, ok = a[0].(string)
		if !ok {
			return fmt.Errorf("%v: prompt is not a string", a[1])
		}
	}
	if len(a) > 1 {
		completeFn, ok = a[1].(string)
		if !ok {
			return fmt.Errorf("%v: complete function name is not a string", a[0])
		}
	}

	src, err := i.os.Readline(prompt, func(line string, pos int) (newLine []string, shared int) {
		completeCtx, completeCtxCancelFn := context.WithTimeout(i.evalContext.ctx, 1*time.Second)
		defer completeCtxCancelFn()
		// TODO: err
		names, shared, _ := completeTrampoline(completeCtx, completeFn, c, i, line, pos)
		return names, shared
	})

	if errors.Is(err, ErrInterrupt) {
		return valueError{"interrupt"}
	} else if errors.Is(err, ErrEOF) {
		return valueError{"eof"}
	} else if err != nil {
		return err
	}

	return src
}

func (i *Interp) eval(c interface{}, a []interface{}) gojq.Iter {
	src, ok := a[0].(string)
	if !ok {
		return gojq.NewIter(fmt.Errorf("%v: src is not a string", a[0]))
	}
	debugFn := ""
	if len(a) >= 2 {
		debugFn, ok = a[1].(string)
		if !ok {
			return gojq.NewIter(fmt.Errorf("%v: debugFn is not a string", a[1]))
		}
	}

	iter, err := i.Eval(i.evalContext.ctx, ScriptMode, c, src, i.evalContext.stdout, debugFn)
	if err != nil {
		return gojq.NewIter(err)
	}

	return iter
}

func (i *Interp) print(c interface{}, a []interface{}) gojq.Iter {
	if _, err := fmt.Fprint(i.evalContext.stdout, c); err != nil {
		return gojq.NewIter(err)
	}
	return gojq.NewIter()
}

func (i *Interp) println(c interface{}, a []interface{}) gojq.Iter {
	if _, err := fmt.Fprintln(i.evalContext.stdout, c); err != nil {
		return gojq.NewIter(err)
	}
	return gojq.NewIter()
}

func (i *Interp) stderr(c interface{}, a []interface{}) gojq.Iter {
	if _, err := fmt.Fprint(i.os.Stderr(), c); err != nil {
		return gojq.NewIter(err)
	}
	return gojq.NewIter()
}

func (i *Interp) debug(c interface{}, a []interface{}) interface{} {
	if i.evalContext.debugFn != "" {
		di, err := i.EvalFunc(i.evalContext.ctx, ScriptMode, c, i.evalContext.debugFn, []interface{}{}, i.evalContext.stdout, "")
		if err != nil {
			return err
		}
		for {
			v, ok := di.Next()
			if !ok {
				break
			}
			if err, ok := v.(error); ok {
				// TODO: how to log?
				fmt.Fprintf(i.os.Stderr(), "%v", err)
			}
		}
	} else {
		// TODO: how to log?
		if err := json.NewEncoder(i.os.Stderr()).Encode([]interface{}{"DEBUG", c}); err != nil {
			return err
		}
	}

	return c
}

func (i *Interp) _completeQuery(c interface{}, a []interface{}) interface{} {
	s, ok := c.(string)
	if !ok {
		return fmt.Errorf("%v: value is not a string", c)
	}

	gq, typ, prefix := BuildCompletionQuery(s)
	queryStr := ""
	if gq != nil {
		queryStr = gq.String()
	}

	return map[string]interface{}{
		"query":  queryStr,
		"type":   string(typ),
		"prefix": prefix,
	}
}

func (i *Interp) _displayName(c interface{}, a []interface{}) interface{} {
	qo, ok := c.(InterpObject)
	if !ok {
		return fmt.Errorf("%v: value is not query object", c)
	}
	return qo.DisplayName()
}

func (i *Interp) _extKeys(c interface{}, a []interface{}) interface{} {
	if v, ok := c.(InterpObject); ok {
		var vs []interface{}
		for _, s := range v.ExtKeys() {
			vs = append(vs, s)
		}
		return vs
	}
	return nil
}

func (i *Interp) makeStateFn(state *interface{}) func(c interface{}, a []interface{}) interface{} {
	return func(c interface{}, a []interface{}) interface{} {
		if len(a) > 0 {
			*state = a[0]
		}
		return *state
	}
}

func (i *Interp) formats(c interface{}, a []interface{}) interface{} {
	allFormats := map[string]*decode.Format{}

	for _, fs := range i.registry.Groups {
		for _, f := range fs {
			if _, ok := allFormats[f.Name]; ok {
				continue
			}
			allFormats[f.Name] = f
		}
	}

	vs := map[string]interface{}{}
	for _, f := range allFormats {
		vf := map[string]interface{}{
			"name":        f.Name,
			"description": f.Description,
			"probe_order": f.ProbeOrder,
		}

		var dependenciesVs []interface{}
		for _, d := range f.Dependencies {
			var dNamesVs []interface{}
			for _, n := range d.Names {
				dNamesVs = append(dNamesVs, n)
			}
			dependenciesVs = append(dependenciesVs, dNamesVs)
		}
		if len(dependenciesVs) > 0 {
			vf["dependencies"] = dependenciesVs
		}
		var groupsVs []interface{}
		for _, n := range f.Groups {
			groupsVs = append(groupsVs, n)
		}
		if len(groupsVs) > 0 {
			vf["groups"] = groupsVs
		}

		vs[f.Name] = vf
	}

	return vs
}

func (i *Interp) history(c interface{}, a []interface{}) interface{} {
	hs, err := i.os.History()
	if err != nil {
		return err
	}
	var vs []interface{}
	for _, s := range hs {
		vs = append(vs, s)
	}
	return vs
}

type bitBufFile struct {
	bb       *bitio.Buffer
	filename string

	decodeDoneFn func()
}

var _ ToBuffer = (*bitBufFile)(nil)

func (bbf *bitBufFile) Display(w io.Writer, opts Options) error {
	_, err := fmt.Fprintf(w, "<%s>\n", bbf.filename)
	return err
}

func (bbf *bitBufFile) ToBuffer() (*bitio.Buffer, error) {
	return bbf.bb.Copy(), nil
}

// def open: #:: string| => buffer
// opens a file for reading from filesystem
func (i *Interp) _open(c interface{}, a []interface{}) interface{} {
	var err error

	opts, err := i.Options()
	if err != nil {
		return err
	}

	var path string
	path, err = toString(c)
	if err != nil {
		return fmt.Errorf("%s: %w", path, err)
	}

	var bEnd int64
	var f fs.File
	if path == "" || path == "-" {
		f = i.os.Stdin()
	} else {
		f, err = i.os.FS().Open(path)
		if err != nil {
			return err
		}
	}

	var fRS io.ReadSeeker
	fFI, err := f.Stat()
	if err != nil {
		return err
	}

	// TODO: ctxreadseeker might leak
	if fFI.Mode().IsRegular() {
		if rs, ok := f.(io.ReadSeeker); ok {
			fRS = ctxreadseeker.New(i.evalContext.ctx, rs)
			bEnd = fFI.Size()
		}
	}

	if fRS == nil {
		buf, err := ioutil.ReadAll(ctxreadseeker.New(i.evalContext.ctx, &ioextra.NopSeeker{Reader: f}))
		if err != nil {
			return err
		}
		fRS = bytes.NewReader(buf)
		bEnd = int64(len(buf))
	}

	// TODO: make nicer
	// we don't want to print any progress things after decode is done
	var decodeDoneFn func()
	if opts.DecodeProgress && opts.REPL && i.os.Stdout().IsTerminal() {
		decodeDone := false
		progressFn := func(r, l int64) {
			if decodeDone {
				return
			}
			fmt.Fprintf(i.os.Stderr(), "\r%.1f%%", (float64(r)/float64(l))*100)
		}
		decodeDoneFn = func() {
			decodeDone = true
			// cleanup when done         100.0%
			fmt.Fprint(i.os.Stderr(), "\r      \r")
		}
		const progressPrecision = 1024
		fRS = progressreadseeker.New(fRS, progressPrecision, bEnd, progressFn)
	}

	const cacheReadAheadSize = 512 * 1024
	aheadRs := aheadreadseeker.New(fRS, cacheReadAheadSize)

	// bb -> aheadreadseeker -> progressreadseeker -> ctxreadseeker -> readerseeker

	bb, err := bitio.NewBufferFromReadSeeker(aheadRs)
	if err != nil {
		return err
	}

	return &bitBufFile{
		bb:           bb,
		filename:     path,
		decodeDoneFn: decodeDoneFn,
	}
}

func (i *Interp) makeDecodeFn(registry *registry.Registry, decodeFormats []*decode.Format) func(c interface{}, a []interface{}) interface{} {
	return func(c interface{}, a []interface{}) interface{} {
		filename := "unnamed"

		// TODO: progress hack
		// would be nice to move progress code into decode but it might be
		// tricky to keep track of absolute positions in the underlaying readers
		// when it uses BitBuf slices, maybe only in Pos()?
		if bbf, ok := c.(*bitBufFile); ok {
			if bbf.decodeDoneFn != nil {
				defer bbf.decodeDoneFn()
			}
			filename = bbf.filename
		}

		bb, err := toBuffer(c)
		if err != nil {
			return err
		}

		opts := map[string]interface{}{}

		if len(a) >= 1 {
			formatName, err := toString(a[0])
			if err != nil {
				return fmt.Errorf("%s: %w", formatName, err)
			}
			decodeFormats, err = registry.Group(formatName)
			if err != nil {
				return fmt.Errorf("%s: %w", formatName, err)
			}
		}

		dv, _, err := decode.Decode("", filename, bb, decodeFormats, decode.DecodeOptions{FormatOptions: opts})
		if dv == nil {
			var decodeFormatsErr decode.DecodeFormatsError
			if errors.As(err, &decodeFormatsErr) {
				var vs []interface{}
				for _, fe := range decodeFormatsErr.Errs {
					vs = append(vs, fe.Value())
				}

				return valueError{vs}
			}

			return valueError{err}
		}

		return makeValueObject(dv)
	}
}

func (i *Interp) makeDisplayFn(fnOpts map[string]interface{}) func(c interface{}, a []interface{}) gojq.Iter {
	return func(c interface{}, a []interface{}) gojq.Iter {
		opts, err := i.Options(append([]interface{}{fnOpts}, a...)...)
		if err != nil {
			return gojq.NewIter(err)
		}

		switch v := c.(type) {
		case Display:
			if err := v.Display(i.evalContext.stdout, opts); err != nil {
				return gojq.NewIter(err)
			}
			return gojq.NewIter()
		case nil, bool, float64, int, string, *big.Int, map[string]interface{}, []interface{}, gojq.JQValue:
			if s, ok := v.(string); ok && opts.RawString {
				fmt.Fprint(i.evalContext.stdout, s)
			} else {
				cj, err := i.NewColorJSON(opts)
				if err != nil {
					return gojq.NewIter(err)
				}
				if err := cj.Marshal(v, i.evalContext.stdout); err != nil {
					return gojq.NewIter(err)
				}
			}
			fmt.Fprint(i.evalContext.stdout, opts.JoinString)

			return gojq.NewIter()
		case error:
			return gojq.NewIter(v)
		default:
			return gojq.NewIter(fmt.Errorf("%+#v: not displayable", c))
		}
	}
}

// TODO: opts and colors?
func (i *Interp) preview(c interface{}, a []interface{}) gojq.Iter {
	opts, err := i.Options(a...)
	if err != nil {
		return gojq.NewIter(err)
	}

	switch v := c.(type) {
	case Preview:
		if err := v.Preview(i.evalContext.stdout, opts); err != nil {
			return gojq.NewIter(err)
		}
		return gojq.NewIter()
	default:
		return gojq.NewIter(fmt.Errorf("%v: not previewable", c))
	}
}

func (i *Interp) hexdump(c interface{}, a []interface{}) gojq.Iter {
	bbr, err := toBufferRange(c)
	if err != nil {
		return gojq.NewIter(err)
	}

	opts, err := i.Options(a...)
	if err != nil {
		return gojq.NewIter(err)
	}

	if err := hexdumpRange(bbr, i.evalContext.stdout, opts); err != nil {
		return gojq.NewIter(err)
	}

	return gojq.NewIter()
}

func (i *Interp) string_(c interface{}, a []interface{}) interface{} {
	bb, err := toBuffer(c)
	if err != nil {
		return err
	}

	sb := &strings.Builder{}
	if _, err := io.Copy(sb, bb); err != nil {
		return err
	}

	return sb.String()
}

func (i *Interp) bytes(c interface{}, a []interface{}) interface{} {
	bb, err := toBuffer(c)
	if err != nil {
		return err
	}
	return newBifBufObject(bb, 8)
}

func (i *Interp) bits(c interface{}, a []interface{}) interface{} {
	bb, err := toBuffer(c)
	if err != nil {
		return err
	}
	return newBifBufObject(bb, 1)
}

func (i *Interp) tovalue(c interface{}, a []interface{}) interface{} {
	v, _ := toValue(i, c)
	return v
}

// func (i *Interp) md5(c interface{}, a []interface{}) interface{} {
// 	bb, _, err := toBuffer(c)
// 	if err != nil {
// 		return err
// 	}

// 	if _, err := io.Copy(md5, bb); err != nil {
// 		return err
// 	}

// 	return md5.Sum(nil)
// }

func (i *Interp) queryEscape(c interface{}, a []interface{}) interface{} {
	s, err := toString(c)
	if err != nil {
		return err
	}
	return url.QueryEscape(s)
}

func (i *Interp) queryUnescape(c interface{}, a []interface{}) interface{} {
	s, err := toString(c)
	if err != nil {
		return err
	}
	u, err := url.QueryUnescape(s)
	if err != nil {
		return err
	}
	return u
}
func (i *Interp) pathEscape(c interface{}, a []interface{}) interface{} {
	s, err := toString(c)
	if err != nil {
		return err
	}
	return url.PathEscape(s)
}

func (i *Interp) pathUnescape(c interface{}, a []interface{}) interface{} {
	s, err := toString(c)
	if err != nil {
		return err
	}
	u, err := url.PathUnescape(s)
	if err != nil {
		return err
	}
	return u
}

func (i *Interp) aesCtr(c interface{}, a []interface{}) interface{} {
	keyBytes, err := toBytes(a[0])
	if err != nil {
		return err
	}

	switch len(keyBytes) {
	case 16, 24, 32:
	default:
		return fmt.Errorf("key length should be 16, 24 or 32 bytes, is %d bytes", len(keyBytes))
	}

	block, err := aes.NewCipher(keyBytes)
	if err != nil {
		return err
	}

	var ivBytes []byte
	if len(a) >= 2 {
		var err error
		ivBytes, err = toBytes(a[1])
		if err != nil {
			return err
		}
		if len(ivBytes) != block.BlockSize() {
			return fmt.Errorf("iv length should be %d bytes, is %d bytes", block.BlockSize(), len(ivBytes))
		}
	} else {
		ivBytes = make([]byte, block.BlockSize())
	}

	bb, err := toBuffer(c)
	if err != nil {
		return err
	}

	buf := &bytes.Buffer{}
	reader := &cipher.StreamReader{S: cipher.NewCTR(block, ivBytes), R: bb}
	if _, err := io.Copy(buf, reader); err != nil {
		return err
	}

	return buf.Bytes()
}

func (i *Interp) find(c interface{}, a []interface{}) gojq.Iter {
	bb, err := toBuffer(c)
	if err != nil {
		return gojq.NewIter(err)
	}

	sbb, err := toBuffer(a[0])
	if err != nil {
		return gojq.NewIter(err)
	}

	log.Printf("sbb: %#+v\n", sbb)

	// TODO: error, bitio.Copy?

	bbBytes := &bytes.Buffer{}
	_, _ = io.Copy(bbBytes, bb)

	sbbBytes := &bytes.Buffer{}
	_, _ = io.Copy(sbbBytes, sbb)

	// log.Printf("bbBytes.Bytes(): %#+v\n", bbBytes.Bytes())
	// log.Printf("sbbBytes.Bytes(): %#+v\n", sbbBytes.Bytes())

	idx := bytes.Index(bbBytes.Bytes(), sbbBytes.Bytes())
	if idx == -1 {
		return gojq.NewIter()
	}

	bbo := newBifBufObject(bb, 8)
	// log.Printf("bbo: %#+v\n", bbo)

	return gojq.NewIter(bbo)
}