From 56f0bc54be601c41a03853ccb7986d42f8de7ce0 Mon Sep 17 00:00:00 2001
From: Robin Heggelund Hansen <git@heghan.org>
Date: Mon, 13 Mar 2023 20:23:24 +0100
Subject: [PATCH] Improve error message when there's something wrong with a
 local dependency.

---
 builder/src/Deps/Solver.hs    | 16 ++++-----
 builder/src/Reporting/Exit.hs | 64 ++++++++++++++++++++++++++++++-----
 2 files changed, 63 insertions(+), 17 deletions(-)

diff --git a/builder/src/Deps/Solver.hs b/builder/src/Deps/Solver.hs
index 8410e8c5..52b98815 100644
--- a/builder/src/Deps/Solver.hs
+++ b/builder/src/Deps/Solver.hs
@@ -171,7 +171,7 @@ data ConstraintSource
 
 -- TODO: Avoid re-reading the gren.json for local dependencies
 resolveToConstraintSource :: Pkg.Name -> PossibleFilePath C.Constraint -> Solver ConstraintSource
-resolveToConstraintSource pkgName possibleFP =
+resolveToConstraintSource expectedPkgName possibleFP =
   Solver $ \state ok back err ->
     case possibleFP of
       PossibleFilePath.Other cons ->
@@ -184,15 +184,15 @@ resolveToConstraintSource pkgName possibleFP =
               let outlinePath = fp </> "gren.json"
               bytes <- File.readUtf8 outlinePath
               case D.fromByteString Outline.decoder bytes of
-                Right (Outline.Pkg (Outline.PkgOutline outlineName _ _ version _ _ _ _)) ->
-                  if outlineName /= pkgName 
-                    then err $ Exit.SolverBadLocalDep pkgName fp
+                Right (Outline.Pkg (Outline.PkgOutline pkgName _ _ version _ _ _ _)) ->
+                  if expectedPkgName /= pkgName
+                    then err $ Exit.SolverBadLocalDepWrongName fp expectedPkgName pkgName
                     else ok state (Local (C.exactly version) fp) back
-                Right _ ->
-                  err $ Exit.SolverBadLocalDep pkgName fp
+                Right (Outline.App _) ->
+                  err $ Exit.SolverBadLocalDepExpectedPkg fp expectedPkgName
                 Left _ ->
-                  err $ Exit.SolverBadLocalDep pkgName fp
-            else err $ Exit.SolverBadLocalDep pkgName fp
+                  err $ Exit.SolverBadLocalDepInvalidGrenJson fp expectedPkgName
+            else err $ Exit.SolverLocalDepNotFound fp expectedPkgName
 
 constraintFromCS :: ConstraintSource -> C.Constraint
 constraintFromCS source =
diff --git a/builder/src/Reporting/Exit.hs b/builder/src/Reporting/Exit.hs
index 24acdc3f..a84d8670 100644
--- a/builder/src/Reporting/Exit.hs
+++ b/builder/src/Reporting/Exit.hs
@@ -992,14 +992,19 @@ outdatedToReport exit =
     OutdatedBadOutline outline ->
       toOutlineReport outline
     OutdatedGitTrouble gitError ->
-      toGitErrorReport "PROBLEM FINDING OUTDATED PACKAGE VERSIONS" gitError $
+      toGitErrorReport
+        "PROBLEM FINDING OUTDATED PACKAGE VERSIONS"
+        gitError
         "I tried to find newer versions of the dependencies specified in your gren.json file."
 
 -- SOLVER
 
 data Solver
   = SolverBadCacheData Pkg.Name V.Version
-  | SolverBadLocalDep Pkg.Name String
+  | SolverBadLocalDepWrongName FilePath Pkg.Name Pkg.Name
+  | SolverBadLocalDepExpectedPkg FilePath Pkg.Name
+  | SolverBadLocalDepInvalidGrenJson FilePath Pkg.Name
+  | SolverLocalDepNotFound FilePath Pkg.Name
   | SolverBadGitOperationUnversionedPkg Pkg.Name Git.Error
   | SolverBadGitOperationVersionedPkg Pkg.Name V.Version Git.Error
   | SolverIncompatibleSolvedVersion Pkg.Name Pkg.Name C.Constraint V.Version
@@ -1026,19 +1031,60 @@ toSolverReport problem =
             \ Hopefully that will get you unstuck, but it will not resolve the root\
             \ problem if a 3rd party tool is modifing cached files for some reason."
         ]
-    SolverBadLocalDep pkg filePath ->
+    SolverBadLocalDepWrongName filePath expectedPkgName actualPkgName ->
       Help.report
         "PROBLEM SOLVING PACKAGE CONSTRAINTS"
         Nothing
-        ( "I need the gren.json of "
-            ++ Pkg.toChars pkg
-            ++ " (located at "
+        ( "You have included "
+            ++ Pkg.toChars expectedPkgName
+            ++ " as a local dependency (located at "
+            ++ filePath
+            ++ ") but the gren.json file says that the package name is "
+            ++ Pkg.toChars actualPkgName
+            ++ "."
+        )
+        [ D.reflow
+            "Verify that the path is correct, and that the name is set correctly."
+        ]
+    SolverBadLocalDepExpectedPkg filePath expectedPkgName ->
+      Help.report
+        "PROBLEM SOLVING PACKAGE CONSTRAINTS"
+        Nothing
+        ( "You have included "
+            ++ Pkg.toChars expectedPkgName
+            ++ " as a local dependency (located at "
+            ++ filePath
+            ++ ") but the gren.json file says that it is an application, and not a package."
+        )
+        [ D.reflow
+            "Verify that the path is correct, and that the project is setup correctly."
+        ]
+    SolverBadLocalDepInvalidGrenJson filePath expectedPkgName ->
+      Help.report
+        "PROBLEM SOLVING PACKAGE CONSTRAINTS"
+        Nothing
+        ( "You have included "
+            ++ Pkg.toChars expectedPkgName
+            ++ " as a local dependency (located at "
+            ++ filePath
+            ++ ") but I'm having trouble parsing its gren.json file."
+        )
+        [ D.reflow
+            "Verify that the path is correct, and that the project is setup correctly. \
+            \It might help to run gren make at this location."
+        ]
+    SolverLocalDepNotFound filePath expectedPkgName ->
+      Help.report
+        "PROBLEM SOLVING PACKAGE CONSTRAINTS"
+        Nothing
+        ( "You have included "
+            ++ Pkg.toChars expectedPkgName
+            ++ " as a local dependency (located at "
             ++ filePath
-            ++ ") to help me search for a set of compatible packages. It seems to be a dependency\
-               \ that resides on your disk."
+            ++ ") but I cannot find a gren.json file at that location."
         )
         [ D.reflow
-            "Verify that the path is correct, that it is defined as a package and that it compiles."
+            "Verify that the path is correct."
         ]
     SolverBadGitOperationUnversionedPkg pkg gitError ->
       toGitErrorReport "PROBLEM SOLVING PACKAGE CONSTRAINTS" gitError $