package main

import (
	"bytes"
	"context"
	"encoding/json"
	"errors"
	"io/fs"
	"os"
	"path"
	"path/filepath"
	"reflect"
	"strings"
	"testing"

	"mesh-delivery-checker/rules"

	"git.novox.be/novox/mesh-delivery/contracts/go/clients/meshdeliverycheckerclient"
	"git.novox.be/novox/mesh-delivery/sdk/buildstep"
	"git.novox.be/novox/mesh-delivery/sdk/seatdefs"
	"git.novox.be/novox/mesh-sdk/go/seatdef"
)

// 1921 (B0, D2): the checking program answers, on its last line, the verdict the rules give the facts in its input, and
// refuses facts of a version it does not read, an input it is not given, and a question it is not asked, naming each.
// 1921 (B0, D3): asked -seats, it answers the seat list of the heads laid for it: a definition a head adds, resolved with
// the parts it includes; what it left out, and why; and an empty list for heads with no definition.
func TestTheCheckingProgramAnswersTheVerdictOfItsFacts(t *testing.T) {
	failing, _ := json.Marshal(rules.Tested{Level: buildstep.LevelUnit, Tests: 3, Failed: []rules.Failure{{Package: "x/a", Test: "TestA", Cause: "a_test.go:9: boom"}}})
	facts := rules.Facts{V: rules.FactsVersion, Group: "feat/x", Heads: "0123456789ab", Members: []rules.Member{{Repository: "novox/x", Number: 3, Head: "h"}},
		Steps: []rules.Step{
			{Repository: "novox/x", Number: 3, Module: "mesh-build-go", Node: "laptop", Level: &buildstep.LevelAnswer{Level: buildstep.LevelUnit, Tests: []json.RawMessage{failing}}},
			{Repository: "novox/x", Number: 3, Failed: &rules.FailedFirst{Machine: "laptop", Words: "novox/x#3 has files in conflict: go.mod"}},
		}}
	dir := t.TempDir()
	write := func(name string, v any) string {
		data, _ := json.Marshal(v)
		p := filepath.Join(dir, name)
		if err := os.WriteFile(p, data, 0o600); err != nil {
			t.Fatal(err)
		}
		return p
	}
	v1 := write("v1.json", facts)
	later := facts
	later.V = rules.FactsVersion + 1
	v2 := write("v2.json", later)
	// The heads as the build node lays them, each at its repository's path: a contracts module of its own defining a seat
	// with a part, and the mesh's own contracts module defining a seat of a domain that is not its (ADR 0636 §5).
	lay := func(name string, files map[string]string) string {
		root := filepath.Join(dir, name)
		for p, body := range files {
			if err := os.MkdirAll(filepath.Dir(filepath.Join(root, p)), 0o755); err != nil {
				t.Fatal(err)
			}
			if err := os.WriteFile(filepath.Join(root, p), []byte(body), 0o600); err != nil {
				t.Fatal(err)
			}
		}
		return root
	}
	contracts := func(module string) string {
		return `{"module": "` + module + `", "build": {"artifacts": [{"name": "go", "kind": "package", "language": "go", "generated-from": "."}]}}`
	}
	heads := lay("heads", map[string]string{
		"novox/x/x-contracts/module.json":                  contracts("x-contracts"),
		"novox/x/x-contracts/seats/node-build-x/seat.json": `{"format":1,"seat":"node-build-x","scope":"node","grain":"whole","domain":"Delivery","decision":"ADR 1","description":"kept","includes":["build"],"verbs":[{"name":"own","input":{"type":"object","properties":{"credentials":{"$ref":"#/defs/Sealed"}}},"answer":{"type":"object"}}],"defs":{"Sealed":{"type":"object"}}}`,
		"novox/x/x-contracts/parts/build.json":             `{"format":1,"part":"build","verbs":[{"name":"current","input":{"type":"object"},"answer":{"type":"object"}}],"events":[{"name":"ended","body":{"type":"object"}}]}`,
		"novox/x/contracts/module.json":                    contracts("mesh-contracts"),
		"novox/x/contracts/seats/mesh-catalog/seat.json":   `{"format":1,"seat":"mesh-catalog","scope":"mesh","grain":"whole","domain":"Delivery","decision":"ADR 1"}`,
	})
	broken := lay("broken", map[string]string{
		"novox/x/x-contracts/module.json":            contracts("x-contracts"),
		"novox/x/x-contracts/seats/broken/seat.json": `{"format":1,"seat":"broken","scope":"nowhere"}`,
	})
	none := filepath.Join(dir, "no-heads")
	if err := os.MkdirAll(filepath.Join(none, "novox/x"), 0o755); err != nil {
		t.Fatal(err)
	}
	for name, c := range map[string]struct {
		args         []string
		input, heads string
		exit         int
		said         string
	}{
		"the seats":         {args: []string{"-seats"}, input: v1, heads: heads},
		"no seats":          {args: []string{"-seats"}, input: v1, heads: none},
		"a seat unparsed":   {args: []string{"-seats"}, input: v1, heads: broken, exit: 2, said: "the seat definition of broken (module x-contracts) at the head of novox/x is not taken"},
		"no heads laid":     {args: []string{"-seats"}, exit: 2, said: buildstep.RunHeadsEnv + " names no directory"},
		"the facts":         {args: []string{"-verdict"}, input: v1},
		"a later version":   {args: []string{"-verdict"}, input: v2, exit: 2, said: "facts of version 2, this checking program reads version 1"},
		"no input":          {args: []string{"-verdict"}, exit: 2, said: buildstep.RunInputEnv + " names no file"},
		"nothing asked":     {input: v1, exit: 2, said: "nothing asked"},
		"an unknown asking": {args: []string{"-judge"}, input: v1, exit: 2, said: "-judge"},
	} {
		var out, errs bytes.Buffer
		exit := run(c.args, func(k string) string {
			switch k {
			case buildstep.RunInputEnv:
				return c.input
			case buildstep.RunHeadsEnv:
				return c.heads
			}
			return ""
		}, &out, &errs)
		if exit != c.exit || !strings.Contains(errs.String(), c.said) {
			t.Errorf("%s: exit %d, said %q; want %d and %q", name, exit, errs.String(), c.exit, c.said)
			continue
		}
		if c.exit != 0 {
			continue
		}
		lines := strings.Split(strings.TrimSpace(out.String()), "\n")
		if c.heads != "" {
			var sa rules.SeatsAnswer
			if err := json.Unmarshal([]byte(lines[len(lines)-1]), &sa); err != nil || sa.V != rules.SeatsVersion || sa.Seats == nil {
				t.Fatalf("%s: the last line %q: %v", name, lines[len(lines)-1], err)
			}
			if c.heads == none {
				if len(sa.Seats) != 0 || len(sa.Left) != 0 {
					t.Errorf("%s: %+v, want an empty list", name, sa)
				}
				continue
			}
			var d struct {
				Seat  string `json:"seat"`
				Verbs []struct {
					Name string `json:"name"`
				} `json:"verbs"`
			}
			if len(sa.Seats) == 1 {
				_ = json.Unmarshal(sa.Seats[0], &d)
			}
			if d.Seat != "node-build-x" || len(d.Verbs) != 2 || len(sa.Left) != 1 || !strings.Contains(sa.Left[0].Why, "whose seats mesh-delivery-contracts defines") {
				t.Errorf("%s: seats %s, left %+v; want node-build-x with its part's verb, and mesh-catalog left out", name, sa.Seats, sa.Left)
			}
			// The group check of 616c42434ac2: a checker from before G (no digests in these facts) writes the answer into the
			// build seat's step state, whose writer refuses a value with a field named like a credential, here a schema's
			// property name; the answer carries no verb's or message's schema and no type only they referred to.
			if len(sa.Seats) == 1 && (bytes.Contains(sa.Seats[0], []byte("credentials")) || bytes.Contains(sa.Seats[0], []byte("Sealed"))) {
				t.Errorf("%s: %s carries a verb's schema to a checker that hands no digests", name, sa.Seats[0])
			}
			continue
		}
		var a rules.Answer
		if err := json.Unmarshal([]byte(lines[len(lines)-1]), &a); err != nil || a.V != rules.AnswerVersion {
			t.Fatalf("%s: the last line %q: %v", name, lines[len(lines)-1], err)
		}
		if want := rules.Judge(facts); !reflect.DeepEqual(a.Verdict, want) || a.Verdict.State != meshdeliverycheckerclient.VerdictFail || len(a.Verdict.Failures) != 2 ||
			a.Verdict.Failures[1].Words != "novox/x#3 has files in conflict: go.mod" || a.Verdict.Machines[0] != "laptop" || a.Verdict.Levels[buildstep.LevelUnit].Run != 3 {
			t.Errorf("%s: the verdict %+v, want %+v", name, a.Verdict, want)
		}
	}
	// Review finding 3 of milestone 47/G: the heads of a real group carry every seat definition the reader holds, unchanged
	// (this repository's own contracts, laid as its head): the answer leaves them all to the checker's list and stays
	// within the bound a run's answer is written under (buildstep.RunInputBound), where the whole list would not.
	t.Run("heads carrying every definition the reader holds unchanged answer none of them, within the bound", func(t *testing.T) {
		real := under{prefix: "novox/mesh-delivery", fs: os.DirFS("../../../..")}
		group := rules.Facts{V: rules.FactsVersion, Members: []rules.Member{{Repository: "novox/mesh-delivery", Head: "h"}}}
		// An empty list of digests answers every definition whole (a checker that hands its list's digests, holding none).
		whole, err := rules.SeatsOf(real, rules.Facts{V: rules.FactsVersion, Members: group.Members, SeatDigests: map[string]string{}})
		if err != nil || len(whole.Seats) < 10 {
			t.Fatalf("the repository's own definitions: %d, %v", len(whole.Seats), err)
		}
		// The reader's digests are of each definition whole, as the seat mesh-catalog answers it; the answer is its judging view.
		group.SeatDigests = wholeDigests(t, real, "novox/mesh-delivery")
		same, err := rules.SeatsOf(real, group)
		answer, _ := json.Marshal(same)
		if err != nil || len(same.Seats) != 0 || same.Same != len(whole.Seats) || len(answer) > buildstep.RunInputBound {
			t.Errorf("unchanged heads answer %d definitions (%d the same), %d bytes; want none, all %d the same, within %d: %v",
				len(same.Seats), same.Same, len(answer), len(whole.Seats), buildstep.RunInputBound, err)
		}
		// Review round 2 of G: a checker from before G (B0's, which makes G's own check) hands no digests, and the answer
		// then keeps each seat's own description only, so a group's whole list stays within the bound; each still parses.
		b0, err := rules.SeatsOf(real, rules.Facts{V: rules.FactsVersion, Members: group.Members})
		if err != nil || len(b0.Seats) != len(whole.Seats) {
			t.Fatalf("B0-shaped facts: %d definitions, %v", len(b0.Seats), err)
		}
		for i, raw := range b0.Seats {
			var own struct {
				Description string `json:"description"`
			}
			_ = json.Unmarshal(whole.Seats[i], &own)
			var d struct {
				Description string            `json:"description"`
				Verbs       []json.RawMessage `json:"verbs"`
				Events      []json.RawMessage `json:"events"`
			}
			_ = json.Unmarshal(raw, &d)
			inner := 0
			for _, m := range append(d.Verbs, d.Events...) {
				inner += strings.Count(string(m), `"description":"`)
			}
			parsed, perr := seatdef.Parse(raw)
			for _, v := range parsed.Verbs {
				if len(v.Input) != 0 || len(v.Answer) != 0 {
					t.Errorf("B0-shaped facts answer %s's verb %s with its schemas; want none", parsed.Seat, v.Name)
				}
			}
			for name := range parsed.Defs {
				if !bytes.Contains(raw, []byte(`"#/defs/`+name+`"`)) {
					t.Errorf("B0-shaped facts answer %s with the type %s, which nothing it keeps refers to", parsed.Seat, name)
				}
			}
			if inner > 0 || d.Description != own.Description || perr != nil {
				t.Errorf("B0-shaped facts answer %s with %d inner descriptions, its own %q: %v; want only its own", raw[:min(len(raw), 80)], inner, d.Description, perr)
			}
		}
		if answer, _ := json.Marshal(b0); len(answer) > buildstep.RunInputBound || len(answer) >= len(mustJSON(t, whole))*3/4 {
			t.Errorf("B0-shaped facts answer %d bytes (whole %d), want within %d and far below the whole", len(answer), len(mustJSON(t, whole)), buildstep.RunInputBound)
		}
		// One definition the heads change is answered alone.
		for seat := range group.SeatDigests {
			group.SeatDigests[seat] = "changed"
			break
		}
		if one, err := rules.SeatsOf(real, group); err != nil || len(one.Seats) != 1 {
			t.Errorf("one changed definition: answered %d, %v", len(one.Seats), err)
		}
	})
	// The lead's ruling after G's group check of 616c42434ac2: with digests given too, a changed definition whose verb input
	// has a property named credentials is answered as the validator and the composer read it, with no such field.
	changed, err := rules.SeatsOf(os.DirFS(heads), rules.Facts{V: rules.FactsVersion, Members: facts.Members,
		SeatDigests: map[string]string{"node-build-x": "changed"}})
	if err != nil || len(changed.Seats) != 1 || bytes.Contains(changed.Seats[0], []byte("credentials")) || bytes.Contains(changed.Seats[0], []byte("Sealed")) {
		t.Errorf("a changed definition with digests given: %d answered, %s, %v; want it alone, with no verb's schema", len(changed.Seats), changed.Seats, err)
	}
	// Review round 1 of milestone 47/B0: the module graph's cycle rule is the program's (ADR 0603 §2, ADR 0656 §5), over the
	// edges the running checker gathers. A cycle the change makes fails; one the trunk has among the same modules is noted.
	web, mail := rules.Edge{From: "web", To: "mail", Kind: rules.EdgeAwaits}, rules.Edge{From: "mail", To: "web", Kind: rules.EdgeAwaits}
	only := func(e rules.Edge, where string) rules.Edge { e.Only = where; return e }
	for _, row := range []struct {
		name  string
		graph rules.Graph
		fails string
		note  string
	}{
		{name: "no cycle", graph: rules.Graph{Trunk: true, Edges: []rules.Edge{web}}, note: "has no cycle"},
		{name: "a cycle the change makes", graph: rules.Graph{Trunk: true, Edges: []rules.Edge{mail, only(web, rules.EdgeChange)}}, fails: "has the cycle mail -> web -> mail"},
		{name: "a cycle the trunk has", graph: rules.Graph{Trunk: true, Edges: []rules.Edge{mail, web}}, note: "which the trunk already has"},
		{name: "the trunk unread", graph: rules.Graph{Edges: []rules.Edge{mail, web}}, fails: "has the cycle mail -> web -> mail"},
		{name: "a base on itself", graph: rules.Graph{Trunk: true, Edges: []rules.Edge{only(rules.Edge{From: "web", To: "web", Kind: rules.EdgeBase}, rules.EdgeChange)}}, fails: "has the cycle web -> web"},
		{name: "an edge only the trunk has", graph: rules.Graph{Trunk: true, Edges: []rules.Edge{mail, only(web, rules.EdgeTrunk)}}, note: "has no cycle"},
	} {
		g := row.graph
		a := rules.Judged(rules.Facts{V: rules.FactsVersion, Steps: []rules.Step{{Graph: &g}}})
		if row.fails != "" && (a.Verdict.State != meshdeliverycheckerclient.VerdictFail || !strings.Contains(a.Verdict.Failed.Words, row.fails)) {
			t.Errorf("%s: verdict %+v, want a fail saying %q", row.name, a.Verdict, row.fails)
		}
		if row.note != "" && (a.Verdict.State != meshdeliverycheckerclient.VerdictPass || !strings.Contains(strings.Join(a.Notes, "\n"), row.note)) {
			t.Errorf("%s: verdict %s, notes %q, want a pass noting %q", row.name, a.Verdict.State, a.Notes, row.note)
		}
	}
}

// under is a directory laid at a repository's path of the heads, as the build node lays a head.
type under struct {
	prefix string
	fs     fs.FS
}

func (u under) Open(name string) (fs.File, error) {
	if name == u.prefix {
		return u.fs.Open(".")
	}
	if rest, ok := strings.CutPrefix(name, u.prefix+"/"); ok {
		return u.fs.Open(rest)
	}
	return nil, &fs.PathError{Op: "open", Path: name, Err: fs.ErrNotExist}
}

func mustJSON(t *testing.T, v any) []byte {
	t.Helper()
	out, err := json.Marshal(v)
	if err != nil {
		t.Fatal(err)
	}
	return out
}

// wholeDigests are the digests of a head's seat definitions whole (rules.SeatDigest), read by the domain SDK as the
// indexer reads them: what a checker's reader holds for heads that change none.
func wholeDigests(t *testing.T, root fs.FS, repository string) map[string]string {
	t.Helper()
	head, err := fs.Sub(root, repository)
	if err != nil {
		t.Fatal(err)
	}
	manifests := map[string]string{}
	_ = fs.WalkDir(head, ".", func(p string, d fs.DirEntry, err error) error {
		if err != nil {
			return err
		}
		if d.IsDir() && (d.Name() == ".git" || d.Name() == "testdata" || d.Name() == "node_modules") {
			return fs.SkipDir
		}
		if !d.IsDir() && d.Name() == "module.json" {
			raw, _ := fs.ReadFile(head, p)
			manifests[path.Dir(p)] = string(raw)
		}
		return nil
	})
	forge := seatdefs.Forge{
		Files: func(_ context.Context, _, _ string, dirs []string) (map[string]map[string]string, error) {
			out := map[string]map[string]string{}
			for _, dir := range dirs {
				files := map[string]string{}
				if err := fs.WalkDir(head, dir, func(p string, d fs.DirEntry, err error) error {
					if err == nil && !d.IsDir() {
						files[strings.TrimPrefix(p, dir+"/")] = ""
					}
					return err
				}); err == nil {
					out[dir] = files
				}
			}
			return out, nil
		},
		File: func(_ context.Context, _, _, file string) ([]byte, error) {
			raw, err := fs.ReadFile(head, file)
			if errors.Is(err, fs.ErrNotExist) {
				return nil, nil
			}
			return raw, err
		},
	}
	out := map[string]string{}
	if len(manifests) == 0 {
		t.Fatalf("no manifest at the head of %s", repository)
	}
	for _, c := range seatdefs.ContractsModules(manifests) {
		defs, _, err := forge.Read(context.Background(), repository, "h", c)
		if err != nil {
			t.Fatal(err)
		}
		for seat, d := range defs {
			raw, _ := json.Marshal(d)
			out[seat] = rules.SeatDigest(raw)
		}
	}
	return out
}