// Copyright 2021 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT

package csv

import (
	"bytes"
	"context"
	"encoding/csv"
	"io"
	"strconv"
	"strings"
	"testing"

	"code.gitea.io/gitea/modules/markup"
	"code.gitea.io/gitea/modules/translation"

	"github.com/stretchr/testify/assert"
)

func TestCreateReader(t *testing.T) {
	rd := CreateReader(bytes.NewReader([]byte{}), ',')
	assert.Equal(t, ',', rd.Comma)
}

func decodeSlashes(t *testing.T, s string) string {
	s = strings.ReplaceAll(s, "\n", "\\n")
	s = strings.ReplaceAll(s, "\"", "\\\"")
	decoded, err := strconv.Unquote(`"` + s + `"`)
	assert.NoError(t, err, "unable to decode string")
	return decoded
}

func TestCreateReaderAndDetermineDelimiter(t *testing.T) {
	cases := []struct {
		csv               string
		expectedRows      [][]string
		expectedDelimiter rune
	}{
		// case 0 - semicolon delimited
		{
			csv: `a;b;c
1;2;3
4;5;6`,
			expectedRows: [][]string{
				{"a", "b", "c"},
				{"1", "2", "3"},
				{"4", "5", "6"},
			},
			expectedDelimiter: ';',
		},
		// case 1 - tab delimited with empty fields
		{
			csv: `col1	col2	col3
a,	b	c
	e	f
g	h	i
j		l
m	n,\t
p	q	r
		u
v	w	x
y\t\t
		`,
			expectedRows: [][]string{
				{"col1", "col2", "col3"},
				{"a,", "b", "c"},
				{"", "e", "f"},
				{"g", "h", "i"},
				{"j", "", "l"},
				{"m", "n,", ""},
				{"p", "q", "r"},
				{"", "", "u"},
				{"v", "w", "x"},
				{"y", "", ""},
				{"", "", ""},
			},
			expectedDelimiter: '\t',
		},
		// case 2 - comma delimited with leading spaces
		{
			csv: ` col1,col2,col3
 a, b, c
d,e,f
 ,h, i
j, ,\x20
 , , `,
			expectedRows: [][]string{
				{"col1", "col2", "col3"},
				{"a", "b", "c"},
				{"d", "e", "f"},
				{"", "h", "i"},
				{"j", "", ""},
				{"", "", ""},
			},
			expectedDelimiter: ',',
		},
	}

	for n, c := range cases {
		rd, err := CreateReaderAndDetermineDelimiter(nil, strings.NewReader(decodeSlashes(t, c.csv)))
		assert.NoError(t, err, "case %d: should not throw error: %v\n", n, err)
		assert.EqualValues(t, c.expectedDelimiter, rd.Comma, "case %d: delimiter should be '%c', got '%c'", n, c.expectedDelimiter, rd.Comma)
		rows, err := rd.ReadAll()
		assert.NoError(t, err, "case %d: should not throw error: %v\n", n, err)
		assert.EqualValues(t, c.expectedRows, rows, "case %d: rows should be equal", n)
	}
}

type mockReader struct{}

func (r *mockReader) Read(buf []byte) (int, error) {
	return 0, io.ErrShortBuffer
}

func TestDetermineDelimiterShortBufferError(t *testing.T) {
	rd, err := CreateReaderAndDetermineDelimiter(nil, &mockReader{})
	assert.Error(t, err, "CreateReaderAndDetermineDelimiter() should throw an error")
	assert.ErrorIs(t, err, io.ErrShortBuffer)
	assert.Nil(t, rd, "CSV reader should be mnil")
}

func TestDetermineDelimiterReadAllError(t *testing.T) {
	rd, err := CreateReaderAndDetermineDelimiter(nil, strings.NewReader(`col1,col2
	a;b
	c@e
	f	g
	h|i
	jkl`))
	assert.NoError(t, err, "CreateReaderAndDetermineDelimiter() shouldn't throw error")
	assert.NotNil(t, rd, "CSV reader should not be mnil")
	rows, err := rd.ReadAll()
	assert.Error(t, err, "RaadAll() should throw error")
	assert.ErrorIs(t, err, csv.ErrFieldCount)
	assert.Empty(t, rows, "rows should be empty")
}

func TestDetermineDelimiter(t *testing.T) {
	cases := []struct {
		csv               string
		filename          string
		expectedDelimiter rune
	}{
		// case 0 - semicolon delmited
		{
			csv:               "a",
			filename:          "test.csv",
			expectedDelimiter: ',',
		},
		// case 1 - single column/row CSV
		{
			csv:               "a",
			filename:          "",
			expectedDelimiter: ',',
		},
		// case 2 - single column, single row CSV w/ tsv file extension (so is tabbed delimited)
		{
			csv:               "1,2",
			filename:          "test.tsv",
			expectedDelimiter: '\t',
		},
		// case 3 - two column, single row CSV w/ no filename, so will guess comma as delimiter
		{
			csv:               "1,2",
			filename:          "",
			expectedDelimiter: ',',
		},
		// case 4 - semi-colon delimited with csv extension
		{
			csv:               "1;2",
			filename:          "test.csv",
			expectedDelimiter: ';',
		},
		// case 5 - tabbed delimited with tsv extension
		{
			csv:               "1\t2",
			filename:          "test.tsv",
			expectedDelimiter: '\t',
		},
		// case 6 - tabbed delimited without any filename
		{
			csv:               "1\t2",
			filename:          "",
			expectedDelimiter: '\t',
		},
		// case 7 - tabs won't work, only commas as every row has same amount of commas
		{
			csv:               "col1,col2\nfirst\tval,seconed\tval",
			filename:          "",
			expectedDelimiter: ',',
		},
		// case 8 - While looks like comma delimited, has psv extension
		{
			csv:               "1,2",
			filename:          "test.psv",
			expectedDelimiter: '|',
		},
		// case 9 - pipe delmiited with no extension
		{
			csv:               "1|2",
			filename:          "",
			expectedDelimiter: '|',
		},
		// case 10 - semi-colon delimited with commas in values
		{
			csv:               "1,2,3;4,5,6;7,8,9\na;b;c",
			filename:          "",
			expectedDelimiter: ';',
		},
		// case 11 - semi-colon delimited with newline in content
		{
			csv: `"1,2,3,4";"a
b";%
c;d;#`,
			filename:          "",
			expectedDelimiter: ';',
		},
		// case 12 - HTML as single value
		{
			csv:               "<br/>",
			filename:          "",
			expectedDelimiter: ',',
		},
		// case 13 - tab delimited with commas in values
		{
			csv: `name	email	note
John Doe	john@doe.com	This,note,had,a,lot,of,commas,to,test,delimiters`,
			filename:          "",
			expectedDelimiter: '\t',
		},
	}

	for n, c := range cases {
		delimiter := determineDelimiter(markup.NewRenderContext(context.Background()).WithRelativePath(c.filename), []byte(decodeSlashes(t, c.csv)))
		assert.EqualValues(t, c.expectedDelimiter, delimiter, "case %d: delimiter should be equal, expected '%c' got '%c'", n, c.expectedDelimiter, delimiter)
	}
}

func TestRemoveQuotedString(t *testing.T) {
	cases := []struct {
		text         string
		expectedText string
	}{
		// case 0 - quoted text with escaped quotes in 1st column
		{
			text: `col1,col2,col3
"quoted ""text"" with
new lines
in first column",b,c`,
			expectedText: `col1,col2,col3
,b,c`,
		},
		// case 1 - quoted text with escaped quotes in 2nd column
		{
			text: `col1,col2,col3
a,"quoted ""text"" with
new lines
in second column",c`,
			expectedText: `col1,col2,col3
a,,c`,
		},
		// case 2 - quoted text with escaped quotes in last column
		{
			text: `col1,col2,col3
a,b,"quoted ""text"" with
new lines
in last column"`,
			expectedText: `col1,col2,col3
a,b,`,
		},
		// case 3 - csv with lots of quotes
		{
			text: `a,"b",c,d,"e
e
e",f
a,bb,c,d,ee ,"f
f"
a,b,"c ""
c",d,e,f`,
			expectedText: `a,,c,d,,f
a,bb,c,d,ee ,
a,b,,d,e,f`,
		},
		// case 4 - csv with pipes and quotes
		{
			text: `Col1 | Col2 | Col3
abc   | "Hello
World"|123
"de

f" | 4.56 | 789`,
			expectedText: `Col1 | Col2 | Col3
abc   | |123
 | 4.56 | 789`,
		},
	}

	for n, c := range cases {
		modifiedText := removeQuotedString(decodeSlashes(t, c.text))
		assert.EqualValues(t, c.expectedText, modifiedText, "case %d: modified text should be equal", n)
	}
}

func TestGuessDelimiter(t *testing.T) {
	cases := []struct {
		csv               string
		expectedDelimiter rune
	}{
		// case 0 - single cell, comma delmited
		{
			csv:               "a",
			expectedDelimiter: ',',
		},
		// case 1 - two cells, comma delimited
		{
			csv:               "1,2",
			expectedDelimiter: ',',
		},
		// case 2 - semicolon delimited
		{
			csv:               "1;2",
			expectedDelimiter: ';',
		},
		// case 3 - tab delimited
		{
			csv:               "1\t2",
			expectedDelimiter: '\t',
		},
		// case 4 - pipe delimited
		{
			csv:               "1|2",
			expectedDelimiter: '|',
		},
		// case 5 - semicolon delimited with commas in text
		{
			csv: `1,2,3;4,5,6;7,8,9
a;b;c`,
			expectedDelimiter: ';',
		},
		// case 6 - semicolon delmited with commas in quoted text
		{
			csv: `"1,2,3,4";"a
b"
c;d`,
			expectedDelimiter: ';',
		},
		// case 7 - HTML
		{
			csv:               "<br/>",
			expectedDelimiter: ',',
		},
		// case 8 - tab delimited with commas in value
		{
			csv: `name	email	note
John Doe	john@doe.com	This,note,had,a,lot,of,commas,to,test,delimiters`,
			expectedDelimiter: '\t',
		},
		// case 9 - tab delimited with new lines in values, commas in values
		{
			csv: `1	"some,""more
""
	quoted,
text,"	a
2	"some,
quoted,\t
	text,"	b
3	"some,
quoted,
	text"	c
4	"some,
quoted,
text,"	d`,
			expectedDelimiter: '\t',
		},
		// case 10 - semicolon delmited with quotes and semicolon in value
		{
			csv: `col1;col2
"this has a literal "" in the text";"and an ; in the text"`,
			expectedDelimiter: ';',
		},
		// case 11 - pipe delimited with quotes
		{
			csv: `Col1 | Col2 | Col3
abc   | "Hello
World"|123
"de
|
f" | 4.56 | 789`,
			expectedDelimiter: '|',
		},
		// case 12 - a tab delimited 6 column CSV, but the values are not quoted and have lots of commas.
		// In the previous bestScore algorithm, this would have picked comma as the delimiter, but now it should guess tab
		{
			csv: `c1	c2	c3	c4	c5	c6
v,k,x,v	ym,f,oa,qn,uqijh,n,s,wvygpo	uj,kt,j,w,i,fvv,tm,f,ddt,b,mwt,e,t,teq,rd,p,a	e,wfuae,t,h,q,im,ix,y	h,mrlu,l,dz,ff,zi,af,emh	,gov,bmfelvb,axp,f,u,i,cni,x,z,v,sh,w,jo,,m,h
k,ohf,pgr,tde,m,s	te,ek,,v,,ic,kqc,dv,w,oi,j,w,gojjr,ug,,l,j,zl	g,qziq,bcajx,zfow,ka,j,re,ohbc	k,nzm,qm,ts,auf	th,elb,lx,l,q,e,qf	asbr,z,k,y,tltobga
g,m,bu,el	h,l,jwi,o,wge,fy,rure,c,g,lcxu,fxte,uns,cl,s,o,t,h,rsoy,f	bq,s,uov,z,ikkhgyg,,sabs,c,hzue	mc,b,,j,t,n	sp,mn,,m,t,dysi,eq,pigb,rfa,z	w,rfli,sg,,o,wjjjf,f,wxdzfk,x,t,p,zy,p,mg,r,l,h
e,ewbkc,nugd,jj,sf,ih,i,n,jo,b,poem,kw,q,i,x,t,e,uug,k	j,xm,sch,ux,h,,fb,f,pq,,mh,,f,v,,oba,w,h,v,eiz,yzd,o,a,c,e,dhp,q	a,pbef,epc,k,rdpuw,cw	k,j,e,d	xf,dz,sviv,w,sqnzew,t,b	v,yg,f,cq,ti,g,m,ta,hm,ym,ii,hxy,p,z,r,e,ga,sfs,r,p,l,aar,w,kox,j
l,d,v,pp,q,j,bxip,w,i,im,qa,o	e,o	h,w,a,a,qzj,nt,qfn,ut,fvhu,ts	hu,q,g,p,q,ofpje,fsqa,frp,p,vih,j,w,k,jx,	ln,th,ka,l,b,vgk,rv,hkx	rj,v,y,cwm,rao,e,l,wvr,ptc,lm,yg,u,k,i,b,zk,b,gv,fls
velxtnhlyuysbnlchosqlhkozkdapjaueexjwrndwb	nglvnv	kqiv	pbshwlmcexdzipopxjyrxhvjalwp	pydvipwlkkpdvbtepahskwuornbsb	qwbacgq
l,y,u,bf,y,m,eals,n,cop,h,g,vs,jga,opt	x,b,zwmn,hh,b,n,pdj,t,d	px	yn,vtd,u,y,b,ps,yo,qqnem,mxg,m,al,rd,c,k,d,q,f	ilxdxa,m,y,,p,p,y,prgmg,q,n,etj,k,ns	b,pl,z,jq,hk
p,gc	jn,mzr,bw	sb,e,r,dy,ur,wzy,r,c,n,yglr,jbdu,r,pqk,k	q,d,,,p,l,euhl,dc,rwh,t,tq,z,h,p,s,t,x,fugr,h	wi,zxb,jcig,o,t,k	mfh,ym,h,e,p,cnvx,uv,zx,x,pq,blt,v,r,u,tr,g,g,xt
nri,p,,t,if,,y,ptlqq	a,i	w,ovli,um,w,f,re,k,sb,w,jy,zf	i,g,p,q,mii,nr,jm,cc	i,szl,k,eg,l,d	,ah,w,b,vh
,,sh,wx,mn,xm,u,d,yy,u,t,m,j,s,b	ogadq,g,y,y,i,h,ln,jda,g,cz,s,rv,r,s,s,le,r,	y,nu,f,nagj	o,h,,adfy,o,nf,ns,gvsvnub,k,b,xyz	v,h,g,ef,y,gb	c,x,cw,x,go,h,t,x,cu,u,qgrqzrcmn,kq,cd,g,rejp,zcq
skxg,t,vay,d,wug,d,xg,sexc	rt	g,ag,mjq,fjnyji,iwa,m,ml,b,ua,b,qjxeoc	be,s,sh,n,jbzxs,g,n,i,h,y,r,be,mfo,u,p	cw,r,,u,zn,eg,r,yac,m,l,edkr,ha,x,g,b,c,tg,c	j,ye,u,ejd,maj,ea,bm,u,iy`,
			expectedDelimiter: '\t',
		},
		// case 13 - a CSV with more than 10 lines and since we only use the first 10 lines, it should still get the delimiter as semicolon
		{
			csv: `col1;col2;col3
1;1;1
2;2;2
3;3;3
4;4;4
5;5;5
6;6;6
7;7;7
8;8;8
9;9;9
10;10;10
11	11	11
12|12|12`,
			expectedDelimiter: ';',
		},
		// case 14 - a really long single line (over 10k) that will get truncated, but since it has commas and semicolons (but more semicolons) it will pick semicolon
		{
			csv:               strings.Repeat("a;b,c;", 1700),
			expectedDelimiter: ';',
		},
		// case 15 - 2 lines that are well over 10k, but since the 2nd line is where this CSV will be truncated (10k sample), it will only use the first line, so semicolon will be picked
		{
			csv:               "col1@col2@col3\na@b@" + strings.Repeat("c", 6000) + "\nd,e," + strings.Repeat("f", 4000),
			expectedDelimiter: '@',
		},
		// case 16 - has all delimiters so should return comma
		{
			csv: `col1,col2;col3@col4|col5	col6
a	b|c@d;e,f`,
			expectedDelimiter: ',',
		},
		// case 16 - nothing works (bad csv) so returns comma by default
		{
			csv: `col1,col2
a;b
c@e
f	g
h|i
jkl`,
			expectedDelimiter: ',',
		},
	}

	for n, c := range cases {
		delimiter := guessDelimiter([]byte(decodeSlashes(t, c.csv)))
		assert.EqualValues(t, c.expectedDelimiter, delimiter, "case %d: delimiter should be equal, expected '%c' got '%c'", n, c.expectedDelimiter, delimiter)
	}
}

func TestGuessFromBeforeAfterQuotes(t *testing.T) {
	cases := []struct {
		csv               string
		expectedDelimiter rune
	}{
		// case 0 - tab delimited with new lines in values, commas in values
		{
			csv: `1	"some,""more
""
	quoted,
text,"	a
2	"some,
quoted,\t
	text,"	b
3	"some,
quoted,
	text"	c
4	"some,
quoted,
text,"	d`,
			expectedDelimiter: '\t',
		},
		// case 1 - semicolon delmited with quotes and semicolon in value
		{
			csv: `col1;col2
"this has a literal "" in the text";"and an ; in the text"`,
			expectedDelimiter: ';',
		},
		// case 2 - pipe delimited with quotes
		{
			csv: `Col1 | Col2 | Col3
abc   | "Hello
World"|123
"de
|
f" | 4.56 | 789`,
			expectedDelimiter: '|',
		},
		// case 3 - a complicated quoted CSV that is semicolon delmiited
		{
			csv: `he; she
"he said, ""hey!"""; "she said, ""hey back!"""
but; "be"`,
			expectedDelimiter: ';',
		},
		// case 4 - no delimiter should be found
		{
			csv:               `a,b`,
			expectedDelimiter: 0,
		},
		// case 5 - no limiter should be found
		{
			csv: `col1
"he said, ""here I am"""`,
			expectedDelimiter: 0,
		},
		// case 6 - delimiter before double quoted string with space
		{
			csv: `col1|col2
a| "he said, ""here I am"""`,
			expectedDelimiter: '|',
		},
		// case 7 - delimiter before double quoted string without space
		{
			csv: `col1|col2
a|"he said, ""here I am"""`,
			expectedDelimiter: '|',
		},
		// case 8 - delimiter after double quoted string with space
		{
			csv: `col1, col2
"abc\n

", def`,
			expectedDelimiter: ',',
		},
		// case 9 - delimiter after double quoted string without space
		{
			csv: `col1,col2
"abc\n

",def`,
			expectedDelimiter: ',',
		},
	}

	for n, c := range cases {
		delimiter := guessFromBeforeAfterQuotes([]byte(decodeSlashes(t, c.csv)))
		assert.EqualValues(t, c.expectedDelimiter, delimiter, "case %d: delimiter should be equal, expected '%c' got '%c'", n, c.expectedDelimiter, delimiter)
	}
}

func TestFormatError(t *testing.T) {
	cases := []struct {
		err             error
		expectedMessage string
		expectsError    bool
	}{
		{
			err: &csv.ParseError{
				Err: csv.ErrFieldCount,
			},
			expectedMessage: "repo.error.csv.invalid_field_count:0",
			expectsError:    false,
		},
		{
			err: &csv.ParseError{
				Err: csv.ErrBareQuote,
			},
			expectedMessage: "repo.error.csv.unexpected:0,0",
			expectsError:    false,
		},
		{
			err:          bytes.ErrTooLarge,
			expectsError: true,
		},
	}

	for n, c := range cases {
		message, err := FormatError(c.err, &translation.MockLocale{})
		if c.expectsError {
			assert.Error(t, err, "case %d: expected an error to be returned", n)
		} else {
			assert.NoError(t, err, "case %d: no error was expected, got error: %v", n, err)
			assert.EqualValues(t, c.expectedMessage, message, "case %d: messages should be equal, expected '%s' got '%s'", n, c.expectedMessage, message)
		}
	}
}
