package main

import (
	"bytes"
	"io"
	"strings"
	"testing"
)

// Fixtures modelled on real open-epg output: ids of the form "Italia 1 HD.it",
// single-line channel/programme elements, "YYYYMMDDHHMMSS +0000" times.

const epgSource1 = `<?xml version="1.0" encoding="UTF-8" ?>
<tv generator-info-name="open-epg">
<channel id="Italia 1 HD.it"><display-name>Italia 1 HD.it</display-name></channel>
<channel id="Rai 1 HD.it"><display-name>Rai 1 HD.it</display-name></channel>
<channel id="Unmatched HD.it"><display-name>Unmatched</display-name></channel>
<programme start="20260101000000 +0000" stop="20260101010000 +0000" channel="Italia 1 HD.it"><title>Show A</title></programme>
<programme start="20260101010000 +0000" stop="20260101020000 +0000" channel="Rai 1 HD.it"><title>Show B</title></programme>
<programme start="20260101020000 +0000" stop="20260101030000 +0000" channel="Unmatched HD.it"><title>Dropped programme</title></programme>
</tv>`

const epgSource2 = `<?xml version="1.0" encoding="UTF-8" ?>
<tv generator-info-name="open-epg-2">
<channel id="Italia 1 HD.it"><display-name>From src2 - duplicate</display-name></channel>
<channel id="TV8 HD.it"><display-name>TV8 HD</display-name></channel>
<programme start="20260102000000 +0000" stop="20260102010000 +0000" channel="Italia 1 HD.it"><title>Src2 dup show</title></programme>
<programme start="20260102010000 +0000" stop="20260102020000 +0000" channel="TV8 HD.it"><title>TV8 show</title></programme>
</tv>`

func runMerge(t *testing.T, tvgIDs []string, sources ...string) string {
	t.Helper()
	rs := make([]io.ReadSeeker, len(sources))
	for i, s := range sources {
		rs[i] = bytes.NewReader([]byte(s))
	}
	var buf bytes.Buffer
	if err := mergeEPG(rs, buildIDMap(tvgIDs), &buf); err != nil {
		t.Fatalf("mergeEPG: %v", err)
	}
	return buf.String()
}

func TestMergeEPG_SingleSourceFiltersAndRewrites(t *testing.T) {
	out := runMerge(t, []string{"Italia 1", "Rai 1"}, epgSource1)

	mustContain(t, out, `<channel id="Italia 1">`)
	mustContain(t, out, `<channel id="Rai 1">`)
	mustNotContain(t, out, `Unmatched HD.it`)
	mustNotContain(t, out, `Dropped programme`)

	mustContain(t, out, `channel="Italia 1"`)
	mustContain(t, out, `channel="Rai 1"`)
	mustContain(t, out, `<title>Show A</title>`)
	mustContain(t, out, `<title>Show B</title>`)
}

func TestMergeEPG_TwoSourcesFirstWinsAndProgrammesScoped(t *testing.T) {
	out := runMerge(t,
		[]string{"Italia 1", "Rai 1", "TV8"},
		epgSource1, epgSource2,
	)

	// All three matched playlist channels should be present, exactly once.
	for _, want := range []string{
		`<channel id="Italia 1">`,
		`<channel id="Rai 1">`,
		`<channel id="TV8">`,
	} {
		if c := strings.Count(out, want); c != 1 {
			t.Errorf("%q appears %d times in output, want 1", want, c)
		}
	}

	// Source 1 owns "Italia 1" — its show appears, src2's must NOT.
	mustContain(t, out, `<title>Show A</title>`)
	mustNotContain(t, out, `Src2 dup show`)
	mustNotContain(t, out, `From src2 - duplicate`) // dedup at channel level too

	// Source 2 owns "TV8" — its programme should appear.
	mustContain(t, out, `<title>TV8 show</title>`)

	// "Unmatched" is not in the playlist tvg-id set.
	mustNotContain(t, out, `Unmatched`)
	mustNotContain(t, out, `Dropped programme`)
}

func TestMergeEPG_EmptyOutputForUnmatchedPlaylist(t *testing.T) {
	out := runMerge(t, []string{"Channel That Does Not Exist"}, epgSource1)

	mustNotContain(t, out, "<channel ")
	mustNotContain(t, out, "<programme ")
	mustContain(t, out, "<tv ") // wrapper still emitted
	mustContain(t, out, "</tv>")
}

func TestMergeEPG_NoSourcesProducesValidEmptyTV(t *testing.T) {
	var buf bytes.Buffer
	if err := mergeEPG(nil, buildIDMap([]string{"Italia 1"}), &buf); err != nil {
		t.Fatalf("mergeEPG: %v", err)
	}
	out := buf.String()
	mustContain(t, out, "<tv ")
	mustContain(t, out, "</tv>")
}

func mustContain(t *testing.T, hay, needle string) {
	t.Helper()
	if !strings.Contains(hay, needle) {
		t.Errorf("expected output to contain %q\n--- output ---\n%s", needle, hay)
	}
}

func mustNotContain(t *testing.T, hay, needle string) {
	t.Helper()
	if strings.Contains(hay, needle) {
		t.Errorf("expected output NOT to contain %q\n--- output ---\n%s", needle, hay)
	}
}