package graph

import (
	"errors"
	"reflect"
	"slices"
	"strings"
	"testing"

	"git.novox.be/novox/mesh-sdk/go/catalogue"
	"git.novox.be/novox/mesh-sdk/go/delivery"
)

// TestGraphEdges: the module graph's cycle, dependents and providers, each from the edges alone (ADR 0603 §2, ADR 0604 §1).
func TestGraphEdges(t *testing.T) {
	t.Run("a node's value", nodeValues)
	fp := "src2:" + strings.Repeat("b", 64)
	node := func(repository, path string, edit func(*Node)) Node {
		n := Node{FP: fp, Repository: repository, Path: path}
		if edit != nil {
			edit(&n)
		}
		return n
	}
	gotool := map[string]Toolchain{"go": {Module: "build-go", Version: "go1", Recipe: "1"}}
	// A base chain, a package and a build module: app stands on base, imports lib's package, is built by build-go.
	g := Graph{
		"build-go": node("novox/mesh-catalog", "modules/build-go", func(n *Node) { n.Toolchains = gotool }),
		"lib":      node("novox/lib", delivery.RootPath, nil),
		"base":     node("novox/mesh-catalog", "modules/base", nil),
		"app": node("novox/mesh-catalog", "modules/app", func(n *Node) {
			n.Bases, n.Packages, n.Toolchains = []string{"base"}, []string{"git.novox.be/novox/lib"}, gotool
		}),
		"top": node("novox/mesh-catalog", "modules/top", func(n *Node) { n.Bases = []string{"app"} }),
		"db":  node("novox/mesh-catalog", "modules/db", func(n *Node) { n.Provides = []string{"database"} }),
		"web": node("novox/mesh-catalog", "modules/web", func(n *Node) {
			n.Requires, n.Awaits = []string{"database", "db"}, []string{"database"}
		}),
	}
	for module, want := range map[string][]string{
		"base":     {"app", "top"},
		"lib":      {"app", "top"},
		"build-go": {"app", "top"}, // build-go's own toolchain edge reaches itself, which is left out
		"top":      nil,
		"db":       nil, // a provision edge is no build edge
	} {
		if got := g.Dependents(module); !reflect.DeepEqual(got, want) {
			t.Errorf("dependents of %s = %v, want %v", module, got, want)
		}
	}
	if got := g.Providers("database"); !reflect.DeepEqual(got, []string{"db"}) {
		t.Errorf("providers of database = %v", got)
	}
	if got := g.Providers("db"); !reflect.DeepEqual(got, []string{"db"}) { // a module provides its own name
		t.Errorf("providers of db = %v", got)
	}
	if got := g.Before("web"); !reflect.DeepEqual(got, []string{"db"}) { // web awaits database, which db provides
		t.Errorf("web waits for %v", got)
	}
	if got := g.Before("top"); !reflect.DeepEqual(got, []string{"app"}) {
		t.Errorf("top waits for %v", got)
	}
	if got := g.Requirers("db"); !reflect.DeepEqual(got, []string{"web"}) {
		t.Errorf("requirers of db = %v", got)
	}
	if g.Publisher("git.novox.be/novox/lib") != "lib" || g.Publisher("git.novox.be/novox/mesh-sdk/go") != "" {
		t.Error("a package's publisher is not the module at its repository and directory")
	}
	// From manifests alone (the check's graph): a requirement answered by a helper at mesh scope is awaited, an optional
	// one is not, and two modules awaiting each other's provision are a cycle.
	offer := func(name string) []catalogue.Offer {
		return []catalogue.Offer{{Name: name, Scope: catalogue.ScopeMesh, AnsweredBy: catalogue.AnsweredByHelper}}
	}
	ms := map[string]catalogue.Manifest{
		"db":  {Module: "db", Provides: offer("database"), Requires: []string{"site", "logs"}, OptionalRequires: map[string]bool{"logs": true}},
		"web": {Module: "web", Provides: offer("site"), Requires: []string{"database"}, Build: &catalogue.Build{On: []catalogue.BuildsOn{{Module: "base"}}}},
	}
	mg := OfManifests(ms)
	if db := mg["db"]; !reflect.DeepEqual(db.Requires, []string{"site"}) || !reflect.DeepEqual(db.Awaits, []string{"site"}) ||
		!reflect.DeepEqual(mg["web"].Bases, []string{"base"}) || !reflect.DeepEqual(db.Provides, []string{"database"}) {
		t.Errorf("the graph of manifests = %+v", mg)
	}
	if got := mg.Cycle(); !reflect.DeepEqual(got, []string{"db", "web", "db"}) {
		t.Errorf("the cycle of manifests = %v", got)
	}
	for name, c := range map[string]struct {
		edit func(Graph)
		want []string
	}{
		"none: a toolchain on itself and a requirement not awaited order nothing": {func(Graph) {}, nil},
		"bases": {func(g Graph) {
			b := g["base"]
			b.Bases = []string{"top"}
			g["base"] = b
		}, []string{"app", "base", "top", "app"}},
		"provisions a -> b -> a": {func(g Graph) {
			d := g["db"]
			d.Requires, d.Awaits = []string{"site"}, []string{"site"}
			g["db"] = d
			w := g["web"]
			w.Provides = []string{"site"}
			g["web"] = w
		}, []string{"db", "web", "db"}},
		"a requirement not awaited is no edge": {func(g Graph) {
			d := g["db"]
			d.Requires = []string{"site"}
			g["db"] = d
			w := g["web"]
			w.Provides = []string{"site"}
			g["web"] = w
		}, nil},
	} {
		h := Graph{}
		for k, v := range g {
			h[k] = v
		}
		c.edit(h)
		if got := h.Cycle(); !reflect.DeepEqual(got, c.want) {
			t.Errorf("%s: cycle = %v, want %v", name, got, c.want)
		}
	}
}

// sampleNode is a graph node with every kind of edge, its lists unsorted.
func sampleNode() Node {
	return Node{FP: "src2:" + strings.Repeat("a", 64), Repository: "novox/mesh-catalog", Path: "modules/gitea",
		Bases: []string{"z-base", "a-base"}, Packages: []string{"git.novox.be/novox/mesh-sdk/go"},
		Toolchains: map[string]Toolchain{"go": {Module: "build-go", Version: "go1.27.1", Recipe: "3"}},
		Provides:   []string{"forge"}, Requires: []string{"postgres-database", "dns"}, Awaits: []string{"postgres-database"}}
}

// nodeValues: a node round-trips with its lists sorted, an unknown version is refused, a node that does not hold is
// refused naming why, and the state is the indexer's graph (ADR 0603 §2).
func nodeValues(t *testing.T) {
	if Bucket != "mesh-delivery-indexer_graph" || Read != "mesh-delivery-indexer.graph" || History != 5 || State != "graph" {
		t.Error("the graph's state differs from the decided layout")
	}
	g := sampleNode()
	data, err := Encode(g)
	if err != nil || !strings.Contains(string(data), `"v":1`) {
		t.Fatalf("encode: %s %v", data, err)
	}
	if got, err := Decode(data); err != nil || !Same(got, g) || !slices.IsSorted(got.Bases) {
		t.Errorf("round trip: %+v %v", got, err)
	}
	if Same(g, Node{None: "x", Repository: "a/b"}) {
		t.Error("different graph nodes are the same")
	}
	for _, in := range []string{`{"none":"x","repository":"a/b"}`, `{"v":2,"none":"x","repository":"a/b"}`} {
		if _, err := Decode([]byte(in)); !errors.Is(err, ErrUnknownVersion) {
			t.Errorf("decode of %s = %v, want ErrUnknownVersion", in, err)
		}
	}
	for name, c := range map[string]struct {
		change func(*Node)
		word   string
	}{
		"both":                              {func(g *Node) { g.None = "why" }, "both"},
		"neither":                           {func(g *Node) { g.FP = "" }, "neither"},
		"an old form":                       {func(g *Node) { g.FP = "src1:x" }, "src2:"},
		"a dotted base":                     {func(g *Node) { g.Bases = []string{"a.b"} }, "a.b"},
		"a foreign package":                 {func(g *Node) { g.Packages = []string{"example.com/x"} }, "example.com/x"},
		"a toolchain of no module":          {func(g *Node) { g.Toolchains = map[string]Toolchain{"go": {Version: "go1", Recipe: "1"}} }, "build module"},
		"a toolchain of no recipe":          {func(g *Node) { g.Toolchains = map[string]Toolchain{"go": {Module: "b", Version: "go1"}} }, "recipe"},
		"awaiting what it does not require": {func(g *Node) { g.Awaits = []string{"other"} }, "other"},
		"no repository":                     {func(g *Node) { g.Repository = "" }, "repositor"},
	} {
		g := sampleNode()
		c.change(&g)
		if _, err := Encode(g); err == nil || !strings.Contains(err.Error(), c.word) {
			t.Errorf("a node with %s: %v, want it refused naming %q", name, err, c.word)
		}
	}
}