package catalogue

import (
	"encoding/json"
	"os"
	"path/filepath"
	"reflect"
	"strings"
	"testing"
)

// TestPlacedDirectoriesKeepTheirPaths is the check novox/hq issue 119 asks for before a definition
// stops naming where its data lives: a converted manifest, resolved on a node with the default root,
// names exactly the paths the manifest before it named. Data that a service is using must not move
// because a definition stopped saying where it was.
//
// Two checkouts: MESH_CATALOGUE_BEFORE, the catalogue as it was, and MESH_CATALOGUE, as it is now.
// Every module in both is resolved with the controller's own rule (dirsFor, dirFill) and compared
// whole — not only the directories, but every string a directory's id was written into. Both
// sides are resolved, so a manifest converted in two steps (issue 119, then issue 174) is judged
// against the paths it named, not the text it used to name them with.
func TestPlacedDirectoriesKeepTheirPaths(t *testing.T) {
	before, after := os.Getenv("MESH_CATALOGUE_BEFORE"), os.Getenv("MESH_CATALOGUE")
	if before == "" || after == "" {
		t.Skip("set MESH_CATALOGUE_BEFORE and MESH_CATALOGUE to two catalogue checkouts to run this")
	}
	found, _ := filepath.Glob(filepath.Join(after, "modules", "*", "module.json"))
	compared := 0
	for _, path := range found {
		module := filepath.Base(filepath.Dir(path))
		old, err := os.ReadFile(filepath.Join(before, "modules", module, "module.json"))
		if err != nil {
			continue // new since; nothing to keep
		}
		now, err := os.ReadFile(path)
		if err != nil {
			t.Fatal(err)
		}
		if string(old) == string(now) {
			continue
		}
		m, err := ParseManifest(now)
		if err != nil {
			t.Errorf("%s: %v", module, err)
			continue
		}
		earlier, err := ParseManifest(old)
		if err != nil {
			t.Errorf("%s before: %v", module, err)
			continue
		}
		var was, is any
		if err := json.Unmarshal(old, &was); err != nil {
			t.Fatal(err)
		}
		if err := json.Unmarshal(now, &is); err != nil {
			t.Fatal(err)
		}
		// Both sides resolved: the manifest before may itself already place some directories
		// (issue 119's conversion), and what must not move is the path a machine sees.
		was = resolvedTree(was, dirsFor(earlier, Rendering{}), module, t)
		resolved := resolvedTree(is, dirsFor(m, Rendering{}), module, t)
		if !reflect.DeepEqual(was, resolved) {
			wasJSON, _ := json.MarshalIndent(was, "", "  ")
			isJSON, _ := json.MarshalIndent(resolved, "", "  ")
			t.Errorf("%s: resolved on the default root, the converted manifest is not the one before it\n--- before\n%s\n--- resolved now\n%s",
				module, firstDifference(string(wasJSON), string(isJSON)), "")
		}
		compared++
	}
	t.Logf("%d converted manifest(s) resolve to the paths they named before", compared)
}

// resolvedTree is the manifest as a machine would see it: every ${dir:…} filled, a pathless
// directory given the path it resolves to, and the placement word removed.
func resolvedTree(node any, dirs map[string]string, module string, t *testing.T) any {
	switch v := node.(type) {
	case map[string]any:
		out := map[string]any{}
		for k, child := range v {
			if k == "place" {
				continue
			}
			out[k] = resolvedTree(child, dirs, module, t)
		}
		if out["type"] == "directory" {
			if _, has := out["path"]; !has {
				if id, ok := out["id"].(string); ok {
					out["path"] = dirs[id]
				}
			}
		}
		return out
	case []any:
		out := make([]any, len(v))
		for i, child := range v {
			out[i] = resolvedTree(child, dirs, module, t)
		}
		return out
	case string:
		filled, err := dirFill(v, dirs, module)
		if err != nil {
			t.Error(err)
		}
		return filled
	}
	return node
}

func firstDifference(a, b string) string {
	al, bl := strings.Split(a, "\n"), strings.Split(b, "\n")
	for i := range al {
		if i >= len(bl) || al[i] != bl[i] {
			from := i - 2
			if from < 0 {
				from = 0
			}
			to := i + 3
			if to > len(al) {
				to = len(al)
			}
			bt := i + 3
			if bt > len(bl) {
				bt = len(bl)
			}
			return "before:\n" + strings.Join(al[from:to], "\n") + "\nnow:\n" + strings.Join(bl[from:bt], "\n")
		}
	}
	return "(the difference is beyond the shorter document)"
}