hugolib: Refactor/-work the permalink/target path logic

This is a pretty fundamental change in Hugo, but absolutely needed if we should have any hope of getting "multiple outputs" done.

This commit's goal is to say:

* Every file target path is created by `createTargetPath`, i.e. one function for all.
* That function takes every page and site parameter into account, to avoid fragile string parsing to uglify etc. later on.
* The path creation logic has full test coverage.
* All permalinks, paginator URLs etc. are then built on top of that same logic.

Fixes #1252
Fixes #2110
Closes #2374
Fixes #1885
Fixes #3102
Fixes #3179
Fixes #1641
Fixes #1989

1 files changed, 16 insertions, 65 deletions

diff --git a/hugolib/site_test.go b/hugolib/site_test.go
index b8a5eb211..8204ee99e 100644
--- a/hugolib/site_test.go
+++ b/hugolib/site_test.go
@@ -958,7 +958,9 @@ func TestRefLinking(t *testing.T) {
 
 	// refLink doesn't use the location of the current page to work out reflinks
 	okresults := map[string]string{
-		"index.md":  "/",
+		// Note: There are no magic in the index.md name. This was fixed in Hugo 0.20.
+		// Before that, index.md would wrongly resolve to "/".
+		"index.md":  "/index/",
 		"common.md": "/level2/common/",
 		"3-root.md": "/level2/level3/3-root/",
 	}
@@ -979,110 +981,59 @@ func TestSourceRelativeLinksing(t *testing.T) {
 	okresults := map[string]resultMap{
 		"index.md": map[string]string{
 			"/docs/rootfile.md":             "/rootfile/",
-			"/docs/index.md":                "/",
 			"rootfile.md":                   "/rootfile/",
-			"index.md":                      "/",
+			"index.md":                      "/index/",
 			"level2/2-root.md":              "/level2/2-root/",
-			"level2/index.md":               "/level2/",
 			"/docs/level2/2-root.md":        "/level2/2-root/",
-			"/docs/level2/index.md":         "/level2/",
 			"level2/level3/3-root.md":       "/level2/level3/3-root/",
-			"level2/level3/index.md":        "/level2/level3/",
 			"/docs/level2/level3/3-root.md": "/level2/level3/3-root/",
-			"/docs/level2/level3/index.md":  "/level2/level3/",
 			"/docs/level2/2-root/":          "/level2/2-root/",
-			"/docs/level2/":                 "/level2/",
 			"/docs/level2/2-root":           "/level2/2-root/",
-			"/docs/level2":                  "/level2/",
 			"/level2/2-root/":               "/level2/2-root/",
-			"/level2/":                      "/level2/",
 			"/level2/2-root":                "/level2/2-root/",
-			"/level2":                       "/level2/",
 		}, "rootfile.md": map[string]string{
 			"/docs/rootfile.md":             "/rootfile/",
-			"/docs/index.md":                "/",
 			"rootfile.md":                   "/rootfile/",
-			"index.md":                      "/",
 			"level2/2-root.md":              "/level2/2-root/",
-			"level2/index.md":               "/level2/",
 			"/docs/level2/2-root.md":        "/level2/2-root/",
-			"/docs/level2/index.md":         "/level2/",
 			"level2/level3/3-root.md":       "/level2/level3/3-root/",
-			"level2/level3/index.md":        "/level2/level3/",
 			"/docs/level2/level3/3-root.md": "/level2/level3/3-root/",
-			"/docs/level2/level3/index.md":  "/level2/level3/",
 		}, "level2/2-root.md": map[string]string{
 			"../rootfile.md":                "/rootfile/",
-			"../index.md":                   "/",
 			"/docs/rootfile.md":             "/rootfile/",
-			"/docs/index.md":                "/",
 			"2-root.md":                     "/level2/2-root/",
-			"index.md":                      "/level2/",
 			"../level2/2-root.md":           "/level2/2-root/",
-			"../level2/index.md":            "/level2/",
 			"./2-root.md":                   "/level2/2-root/",
-			"./index.md":                    "/level2/",
-			"/docs/level2/index.md":         "/level2/",
 			"/docs/level2/2-root.md":        "/level2/2-root/",
 			"level3/3-root.md":              "/level2/level3/3-root/",
-			"level3/index.md":               "/level2/level3/",
-			"../level2/level3/index.md":     "/level2/level3/",
 			"../level2/level3/3-root.md":    "/level2/level3/3-root/",
-			"/docs/level2/level3/index.md":  "/level2/level3/",
 			"/docs/level2/level3/3-root.md": "/level2/level3/3-root/",
 		}, "level2/index.md": map[string]string{
 			"../rootfile.md":                "/rootfile/",
-			"../index.md":                   "/",
 			"/docs/rootfile.md":             "/rootfile/",
-			"/docs/index.md":                "/",
 			"2-root.md":                     "/level2/2-root/",
-			"index.md":                      "/level2/",
 			"../level2/2-root.md":           "/level2/2-root/",
-			"../level2/index.md":            "/level2/",
 			"./2-root.md":                   "/level2/2-root/",
-			"./index.md":                    "/level2/",
-			"/docs/level2/index.md":         "/level2/",
 			"/docs/level2/2-root.md":        "/level2/2-root/",
 			"level3/3-root.md":              "/level2/level3/3-root/",
-			"level3/index.md":               "/level2/level3/",
-			"../level2/level3/index.md":     "/level2/level3/",
 			"../level2/level3/3-root.md":    "/level2/level3/3-root/",
-			"/docs/level2/level3/index.md":  "/level2/level3/",
 			"/docs/level2/level3/3-root.md": "/level2/level3/3-root/",
 		}, "level2/level3/3-root.md": map[string]string{
-			"../../rootfile.md":      "/rootfile/",
-			"../../index.md":         "/",
-			"/docs/rootfile.md":      "/rootfile/",
-			"/docs/index.md":         "/",
-			"../2-root.md":           "/level2/2-root/",
-			"../index.md":            "/level2/",
-			"/docs/level2/2-root.md": "/level2/2-root/",
-			"/docs/level2/index.md":  "/level2/",
-			"3-root.md":              "/level2/level3/3-root/",
-			"index.md":               "/level2/level3/",
-			"./3-root.md":            "/level2/level3/3-root/",
-			"./index.md":             "/level2/level3/",
-			//			"../level2/level3/3-root.md":    "/level2/level3/3-root/",
-			//			"../level2/level3/index.md":     "/level2/level3/",
+			"../../rootfile.md":             "/rootfile/",
+			"/docs/rootfile.md":             "/rootfile/",
+			"../2-root.md":                  "/level2/2-root/",
+			"/docs/level2/2-root.md":        "/level2/2-root/",
+			"3-root.md":                     "/level2/level3/3-root/",
+			"./3-root.md":                   "/level2/level3/3-root/",
 			"/docs/level2/level3/3-root.md": "/level2/level3/3-root/",
-			"/docs/level2/level3/index.md":  "/level2/level3/",
 		}, "level2/level3/index.md": map[string]string{
-			"../../rootfile.md":      "/rootfile/",
-			"../../index.md":         "/",
-			"/docs/rootfile.md":      "/rootfile/",
-			"/docs/index.md":         "/",
-			"../2-root.md":           "/level2/2-root/",
-			"../index.md":            "/level2/",
-			"/docs/level2/2-root.md": "/level2/2-root/",
-			"/docs/level2/index.md":  "/level2/",
-			"3-root.md":              "/level2/level3/3-root/",
-			"index.md":               "/level2/level3/",
-			"./3-root.md":            "/level2/level3/3-root/",
-			"./index.md":             "/level2/level3/",
-			//			"../level2/level3/3-root.md":    "/level2/level3/3-root/",
-			//			"../level2/level3/index.md":     "/level2/level3/",
+			"../../rootfile.md":             "/rootfile/",
+			"/docs/rootfile.md":             "/rootfile/",
+			"../2-root.md":                  "/level2/2-root/",
+			"/docs/level2/2-root.md":        "/level2/2-root/",
+			"3-root.md":                     "/level2/level3/3-root/",
+			"./3-root.md":                   "/level2/level3/3-root/",
 			"/docs/level2/level3/3-root.md": "/level2/level3/3-root/",
-			"/docs/level2/level3/index.md":  "/level2/level3/",
 		},
 	}