package client

import "testing"

const (
	hashV1  = "sha256:aaa"
	hashV2  = "sha256:bbb"
	hashMod = "sha256:localmod"
)

func testPathFor(typ, name string) string { return "/home/u/target/" + typ + "/" + name }

func manifestWith(entries map[string]*ManifestItem) *Manifest {
	m := NewManifest()
	for k, v := range entries {
		m.Items[k] = v
	}
	return m
}

// TestPlanMatrix walks the complete three-state matrix (disk × upstream)
// plus the missing-disk restore cases, asserting the single planned action.
func TestPlanMatrix(t *testing.T) {
	type disk string
	const (
		diskNone    disk = "missing"
		diskClean   disk = "unmodified"
		diskMod     disk = "user-modified"
		diskForeign disk = "never-managed"
	)
	type upstream string
	const (
		upAdded   upstream = "added"
		upChanged upstream = "changed"
		upSame    upstream = "unchanged"
		upGone    upstream = "removed"
		upAbsent  upstream = "not-in-repo"
	)

	cases := []struct {
		disk disk
		up   upstream
		want Action
	}{
		{diskNone, upAdded, ActDeploy},
		{diskClean, upAdded, ActSkip},
		{diskMod, upAdded, ActSkip},
		{diskForeign, upAdded, ActSkip},

		{diskNone, upChanged, ActUpdate},
		{diskClean, upChanged, ActUpdate},
		{diskMod, upChanged, ActSkip},
		{diskForeign, upChanged, ActSkip},

		{diskNone, upSame, ActUpdate},
		{diskClean, upSame, ActKeep},
		{diskMod, upSame, ActSkip},
		{diskForeign, upSame, ActSkip},

		{diskNone, upGone, ActRemove},
		{diskClean, upGone, ActRemove},
		{diskMod, upGone, ActSkip},
		{diskForeign, upGone, ActSkip},

		{diskClean, upAbsent, ActLeave},
		{diskNone, upAbsent, ActKeep}, // marker for "no plan entry at all"
	}

	for _, tc := range cases {
		name := string(tc.disk) + "/" + string(tc.up)
		t.Run(name, func(t *testing.T) {
			key := manifestKey("skills", "alpha")
			var items []PlannedItem
			manifest := NewManifest()
			diskFacts := map[string]DiskFact{}

			switch tc.up {
			case upAdded:
				items = append(items, PlannedItem{Type: "skills", Name: "alpha", RelPath: "skills/alpha", Hash: hashV1})
			case upChanged, upSame:
				hash := hashV2
				if tc.up == upSame {
					hash = hashV1
				}
				items = append(items, PlannedItem{Type: "skills", Name: "alpha", RelPath: "skills/alpha", Hash: hash})
				manifest.Items[key] = &ManifestItem{Name: "alpha", Type: "skills", Hash: hashV1}
			case upGone:
				manifest.Items[key] = &ManifestItem{Name: "alpha", Type: "skills", Hash: hashV1}
			case upAbsent:
				// neither inventory nor manifest
			}

			switch tc.disk {
			case diskNone:
			case diskClean:
				diskFacts[key] = DiskFact{Exists: true, Hash: hashV1}
			case diskMod, diskForeign:
				diskFacts[key] = DiskFact{Exists: true, Hash: hashMod}
			}

			plan := Plan(items, manifest, diskFacts, testPathFor)
			if tc.disk == diskNone && tc.up == upAbsent {
				if len(plan) != 0 {
					t.Fatalf("a key present nowhere must produce no entry, got %+v", plan)
				}
				return
			}
			if len(plan) != 1 {
				t.Fatalf("want exactly 1 entry, got %d: %+v", len(plan), plan)
			}
			if plan[0].Action != tc.want {
				t.Errorf("action = %s, want %s (reason: %s)", plan[0].Action, tc.want, plan[0].Reason)
			}
			if plan[0].DstPath != testPathFor("skills", "alpha") {
				t.Errorf("DstPath not mapped: %q", plan[0].DstPath)
			}
			if tc.want == ActSkip || tc.want == ActLeave {
				if plan[0].Reason == "" {
					t.Error("skip/leave entries must carry a reason")
				}
			}
		})
	}
}

// TestPlanMixedFixture combines several states in one plan and asserts the
// full deterministic output.
func TestPlanMixedFixture(t *testing.T) {
	items := []PlannedItem{
		{Type: "commands", Name: "deploy", RelPath: "commands/deploy.md", Hash: hashV1},
		{Type: "skills", Name: "fresh", RelPath: "skills/fresh", Hash: hashV1},
		{Type: "skills", Name: "tweaked", RelPath: "skills/tweaked", Hash: hashV2},
		{Type: "skills", Name: "keeper", RelPath: "skills/keeper", Hash: hashV1},
		{Type: "agents", Name: "helper", RelPath: "agents/helper.md", Hash: hashV1},
	}
	manifest := manifestWith(map[string]*ManifestItem{
		"skills/tweaked": {Name: "tweaked", Type: "skills", Hash: hashV1},
		"skills/goner":   {Name: "goner", Type: "skills", Hash: hashV1},
		"skills/keeper":  {Name: "keeper", Type: "skills", Hash: hashV1},
		"skills/blocked": {Name: "blocked", Type: "skills", Hash: hashV1},
		"agents/helper":  {Name: "helper", Type: "agents", Hash: hashV1},
	})
	disk := map[string]DiskFact{
		"skills/fresh":    {Exists: true, Hash: hashMod}, // never-managed × added
		"skills/tweaked":  {Exists: true, Hash: hashMod}, // user-modified × changed
		"skills/goner":    {Exists: true, Hash: hashV1},  // unmodified × removed
		"skills/keeper":   {Exists: true, Hash: hashV1},  // unmodified × unchanged
		"skills/blocked":  {Exists: true, Hash: hashMod}, // user-modified × removed
		"skills/mine":     {Exists: true},                // never-managed × absent
		"commands/deploy": {},                            // missing × added
		"agents/helper":   {Exists: true, Hash: hashV1},  // unmodified × unchanged
	}

	plan := Plan(items, manifest, disk, testPathFor)
	got := map[string]Action{}
	for _, e := range plan {
		got[e.Type+"/"+e.Name] = e.Action
	}
	want := map[string]Action{
		"commands/deploy": ActDeploy,
		"skills/fresh":    ActSkip,
		"skills/tweaked":  ActSkip,
		"agents/helper":   ActKeep,
		"skills/goner":    ActRemove,
		"skills/keeper":   ActKeep,
		"skills/blocked":  ActSkip,
		"skills/mine":     ActLeave,
	}
	if len(got) != len(want) {
		t.Fatalf("plan has %d entries, want %d: %+v", len(got), len(want), plan)
	}
	for key, action := range want {
		if got[key] != action {
			t.Errorf("%s: action = %s, want %s", key, got[key], action)
		}
	}

	sorted := true
	for i := 1; i < len(plan); i++ {
		prev := plan[i-1].Type + "/" + plan[i-1].Name
		curr := plan[i].Type + "/" + plan[i].Name
		if prev > curr {
			sorted = false
		}
	}
	if !sorted {
		t.Error("plan must be deterministically sorted by type/name")
	}
}

// TestPlanPureGuarantee compiles the purity contract: planning identical
// inputs twice yields identical plans, and no input is mutated.
func TestPlanPureGuarantee(t *testing.T) {
	items := []PlannedItem{{Type: "skills", Name: "a", RelPath: "skills/a", Hash: hashV1}}
	manifest := manifestWith(map[string]*ManifestItem{"skills/b": {Name: "b", Type: "skills", Hash: hashV1}})
	disk := map[string]DiskFact{"skills/b": {Exists: true, Hash: hashV1}}

	p1 := Plan(items, manifest, disk, testPathFor)
	p2 := Plan(items, manifest, disk, testPathFor)
	if len(p1) != len(p2) {
		t.Fatal("same inputs must yield same plan length")
	}
	for i := range p1 {
		if p1[i] != p2[i] {
			t.Fatalf("plan not deterministic at %d: %+v vs %+v", i, p1[i], p2[i])
		}
	}
	if manifest.Items["skills/b"] == nil || len(items) != 1 {
		t.Error("planner must not mutate its inputs")
	}
}