package gitea

import (
	"testing"
)

func TestBuildPositionToLineMap_SingleHunk(t *testing.T) {
	// @@ -16,4 +16,5 @@  ← position 1
	// context           ← position 2, new line 16
	//-deleted           ← position 3, no new line
	//+added             ← position 4, new line 17
	// context           ← position 5, new line 18
	diff := `diff --git a/file.go b/file.go
index abc..def 100644
--- a/file.go
+++ b/file.go
@@ -16,4 +16,5 @@ func example() {
 context line
-deleted line
+added line
 context after
`
	pm := BuildPositionToLineMap(diff)

	tests := []struct {
		pos      int
		wantLine int
	}{
		{2, 16}, // context line -> new line 16
		{4, 17}, // added line -> new line 17
		{5, 18}, // context after -> new line 18
	}
	for _, tt := range tests {
		got, err := pm.Translate("file.go", tt.pos)
		if err != nil {
			t.Errorf("Translate(file.go, %d): unexpected error: %v", tt.pos, err)
			continue
		}
		if got != tt.wantLine {
			t.Errorf("Translate(file.go, %d) = %d, want %d", tt.pos, got, tt.wantLine)
		}
	}
}

func TestBuildPositionToLineMap_MultipleHunks(t *testing.T) {
	diff := `diff --git a/file.go b/file.go
--- a/file.go
+++ b/file.go
@@ -1,3 +1,3 @@ package main
 line1
-old
+new
@@ -10,3 +10,4 @@ func foo() {
 func foo() {
+	// added
 	return
 }
`
	pm := BuildPositionToLineMap(diff)

	tests := []struct {
		pos      int
		wantLine int
	}{
		// First hunk: @@ is pos 1
		{2, 1},  // " line1" -> new line 1
		{4, 2},  // "+new" -> new line 2
		// Second hunk: @@ is pos 5 (continues from 4)
		// Wait: first hunk has pos 1(@@ hdr), 2(" line1"), 3("-old"), 4("+new")
		// Second hunk @@ is pos 5
		{6, 10}, // " func foo() {" -> new line 10
		{7, 11}, // "+\t// added" -> new line 11
		{8, 12}, // " \treturn" -> new line 12
		{9, 13}, // " }" -> new line 13
	}
	for _, tt := range tests {
		got, err := pm.Translate("file.go", tt.pos)
		if err != nil {
			t.Errorf("Translate(file.go, %d): unexpected error: %v", tt.pos, err)
			continue
		}
		if got != tt.wantLine {
			t.Errorf("Translate(file.go, %d) = %d, want %d", tt.pos, got, tt.wantLine)
		}
	}
}

func TestBuildPositionToLineMap_DeletionTargeted(t *testing.T) {
	diff := `diff --git a/file.go b/file.go
--- a/file.go
+++ b/file.go
@@ -1,4 +1,3 @@ package main
 line1
-deleted
 line3
`
	pm := BuildPositionToLineMap(diff)

	// Position 3 is the deletion line "-deleted" — should map to nearest below
	// Position 4 is " line3" which is new line 2
	got, err := pm.Translate("file.go", 3)
	if err != nil {
		t.Fatalf("Translate(file.go, 3): unexpected error: %v", err)
	}
	if got != 2 {
		t.Errorf("Translate(file.go, 3) = %d, want 2 (nearest non-deletion below)", got)
	}
}

func TestBuildPositionToLineMap_DeletionAtEnd(t *testing.T) {
	// If a deletion line is at the end with no subsequent non-deletion line, error
	diff := `diff --git a/file.go b/file.go
--- a/file.go
+++ b/file.go
@@ -1,3 +1,2 @@ package main
 line1
 line2
-deleted at end
`
	pm := BuildPositionToLineMap(diff)

	_, err := pm.Translate("file.go", 4)
	if err == nil {
		t.Error("expected error for deletion at end with no subsequent line")
	}
}

func TestBuildPositionToLineMap_NewFile(t *testing.T) {
	diff := `diff --git a/new.go b/new.go
new file mode 100644
--- /dev/null
+++ b/new.go
@@ -0,0 +1,3 @@
+package main
+
+func init() {}
`
	pm := BuildPositionToLineMap(diff)

	tests := []struct {
		pos      int
		wantLine int
	}{
		{2, 1}, // "+package main" -> line 1
		{3, 2}, // "+" (empty line) -> line 2
		{4, 3}, // "+func init() {}" -> line 3
	}
	for _, tt := range tests {
		got, err := pm.Translate("new.go", tt.pos)
		if err != nil {
			t.Errorf("Translate(new.go, %d): unexpected error: %v", tt.pos, err)
			continue
		}
		if got != tt.wantLine {
			t.Errorf("Translate(new.go, %d) = %d, want %d", tt.pos, got, tt.wantLine)
		}
	}
}

func TestBuildPositionToLineMap_DeletedFile(t *testing.T) {
	diff := `diff --git a/old.go b/old.go
deleted file mode 100644
--- a/old.go
+++ /dev/null
@@ -1,3 +0,0 @@
-package main
-
-func old() {}
`
	pm := BuildPositionToLineMap(diff)

	// Deleted file has no new-file lines; positions should error
	_, err := pm.Translate("old.go", 2)
	if err == nil {
		t.Error("expected error for deleted file position")
	}
}

func TestBuildPositionToLineMap_BinaryFile(t *testing.T) {
	diff := `diff --git a/image.png b/image.png
Binary files /dev/null and b/image.png differ
diff --git a/code.go b/code.go
--- a/code.go
+++ b/code.go
@@ -1,2 +1,3 @@
 package main
+// added
 func main() {}
`
	pm := BuildPositionToLineMap(diff)

	// Binary file should not be in the map
	_, err := pm.Translate("image.png", 1)
	if err == nil {
		t.Error("expected error for binary file")
	}

	// code.go should still work
	got, err := pm.Translate("code.go", 3)
	if err != nil {
		t.Fatalf("Translate(code.go, 3): unexpected error: %v", err)
	}
	if got != 2 {
		t.Errorf("Translate(code.go, 3) = %d, want 2", got)
	}
}

func TestBuildPositionToLineMap_OutOfRange(t *testing.T) {
	diff := `diff --git a/file.go b/file.go
--- a/file.go
+++ b/file.go
@@ -1,2 +1,2 @@
 line1
-old
+new
`
	pm := BuildPositionToLineMap(diff)

	// Position 0 is invalid
	_, err := pm.Translate("file.go", 0)
	if err == nil {
		t.Error("expected error for position 0")
	}

	// Position 5 is out of range (only positions 1-4 exist)
	_, err = pm.Translate("file.go", 5)
	if err == nil {
		t.Error("expected error for position 5 (out of range)")
	}

	// Unknown file
	_, err = pm.Translate("unknown.go", 1)
	if err == nil {
		t.Error("expected error for unknown file")
	}
}

func TestBuildPositionToLineMap_MultipleFiles(t *testing.T) {
	diff := `diff --git a/a.go b/a.go
--- a/a.go
+++ b/a.go
@@ -1,2 +1,3 @@
 package a
+// file a
 func aFunc() {}
diff --git a/b.go b/b.go
--- a/b.go
+++ b/b.go
@@ -1,2 +1,3 @@
 package b
+// file b
 func bFunc() {}
`
	pm := BuildPositionToLineMap(diff)

	// a.go: pos 3 is "+// file a" -> new line 2
	got, err := pm.Translate("a.go", 3)
	if err != nil {
		t.Fatalf("Translate(a.go, 3): %v", err)
	}
	if got != 2 {
		t.Errorf("Translate(a.go, 3) = %d, want 2", got)
	}

	// b.go: pos 3 is "+// file b" -> new line 2
	// Note: position resets per file
	got, err = pm.Translate("b.go", 3)
	if err != nil {
		t.Fatalf("Translate(b.go, 3): %v", err)
	}
	if got != 2 {
		t.Errorf("Translate(b.go, 3) = %d, want 2", got)
	}
}

func TestTranslate_HunkHeaderPosition_SingleHunk(t *testing.T) {
	// Position 1 is the @@ hunk-header line.
	// It should resolve to the first context/addition line below (new line 16).
	diff := `diff --git a/file.go b/file.go
index abc..def 100644
--- a/file.go
+++ b/file.go
@@ -16,4 +16,5 @@ func example() {
 context line
-deleted line
+added line
 context after
`
	pm := BuildPositionToLineMap(diff)

	got, err := pm.Translate("file.go", 1)
	if err != nil {
		t.Fatalf("Translate(file.go, 1): unexpected error: %v", err)
	}
	if got != 16 {
		t.Errorf("Translate(file.go, 1) = %d, want 16 (first context/addition line in hunk)", got)
	}
}

func TestTranslate_HunkHeaderPosition_MultiHunk(t *testing.T) {
	// First hunk: @@ is pos 1, then " line1" (pos 2), "-old" (pos 3), "+new" (pos 4)
	// Second hunk: @@ is pos 5, then " func foo() {" (pos 6), "+// added" (pos 7), etc.
	// Translating position 5 (second @@) should resolve to new line 10.
	diff := `diff --git a/file.go b/file.go
--- a/file.go
+++ b/file.go
@@ -1,3 +1,3 @@ package main
 line1
-old
+new
@@ -10,3 +10,4 @@ func foo() {
 func foo() {
+	// added
 	return
 }
`
	pm := BuildPositionToLineMap(diff)

	// Position 5 is the second @@ hunk-header — should resolve to new line 10
	got, err := pm.Translate("file.go", 5)
	if err != nil {
		t.Fatalf("Translate(file.go, 5): unexpected error: %v", err)
	}
	if got != 10 {
		t.Errorf("Translate(file.go, 5) = %d, want 10 (first context/addition line in second hunk)", got)
	}

	// Also verify first hunk header at position 1 resolves to new line 1
	got, err = pm.Translate("file.go", 1)
	if err != nil {
		t.Fatalf("Translate(file.go, 1): unexpected error: %v", err)
	}
	if got != 1 {
		t.Errorf("Translate(file.go, 1) = %d, want 1 (first context/addition line in first hunk)", got)
	}
}

func TestTranslate_HunkHeaderPosition_NewFile(t *testing.T) {
	// New file: @@ -0,0 +1,3 @@ is position 1.
	// Should resolve to new line 1 (the first addition).
	diff := `diff --git a/new.go b/new.go
new file mode 100644
--- /dev/null
+++ b/new.go
@@ -0,0 +1,3 @@
+package main
+
+func init() {}
`
	pm := BuildPositionToLineMap(diff)

	got, err := pm.Translate("new.go", 1)
	if err != nil {
		t.Fatalf("Translate(new.go, 1): unexpected error: %v", err)
	}
	if got != 1 {
		t.Errorf("Translate(new.go, 1) = %d, want 1 (first addition line)", got)
	}
}