package db

import (
	"context"
	"errors"
	"testing"

	"sourcecraft.dev/bigbes/sr-ht-spec/core"
)

func TestProposalOpenAndRead(t *testing.T) {
	s, _, cleanup := newTestStore(t)
	defer cleanup()
	ctx := context.Background()

	space := mkSpace(t, s, ctx, "bigbes", "rfcs")
	p := mkProposal(t, s, ctx, space.ID, "Add storage model section")

	if p.ID == 0 {
		t.Fatal("expected a non-zero proposal id")
	}
	if p.Branch != ProposalBranch(p.ID) {
		t.Fatalf("branch = %q, want %q", p.Branch, ProposalBranch(p.ID))
	}
	if p.State != core.StateOpen {
		t.Fatalf("state = %q, want open", p.State)
	}
	if p.Approval != "" || p.MergedRev != "" || p.Resolved != nil {
		t.Fatalf("a fresh proposal must not be resolved: %+v", p)
	}

	got, err := s.GetProposal(ctx, p.ID)
	if err != nil {
		t.Fatalf("get proposal: %v", err)
	}
	if got.Title != p.Title || got.Rationale != "because" || got.BaseRev != p.BaseRev {
		t.Fatalf("round-trip mismatch: %+v", got)
	}
	if got.Agent != "claude-code/spec-writer" || got.AgentSession == "" {
		t.Fatalf("provenance lost: %+v", got)
	}
	if got.Branch != p.Branch || got.State != core.StateOpen {
		t.Fatalf("unexpected proposal: %+v", got)
	}

	if _, err := s.GetProposal(ctx, 99999); !errors.Is(err, ErrNotFound) {
		t.Fatalf("missing proposal = %v, want ErrNotFound", err)
	}

	// An empty rationale round-trips as "" rather than surfacing a NULL.
	bare, err := s.OpenProposal(ctx, &Proposal{
		SpaceID: space.ID, Title: "no rationale", BaseRev: "abc",
		Agent: "a", AgentSession: "s",
	})
	if err != nil {
		t.Fatalf("open bare proposal: %v", err)
	}
	got, err = s.GetProposal(ctx, bare.ID)
	if err != nil {
		t.Fatalf("get bare proposal: %v", err)
	}
	if got.Rationale != "" {
		t.Fatalf("rationale = %q, want empty", got.Rationale)
	}
}

func TestProposalListByState(t *testing.T) {
	s, _, cleanup := newTestStore(t)
	defer cleanup()
	ctx := context.Background()

	space := mkSpace(t, s, ctx, "bigbes", "rfcs")
	first := mkProposal(t, s, ctx, space.ID, "first")
	second := mkProposal(t, s, ctx, space.ID, "second")
	third := mkProposal(t, s, ctx, space.ID, "third")

	open, err := s.ListProposalsByState(ctx, core.StateOpen, 0)
	if err != nil {
		t.Fatalf("list open: %v", err)
	}
	if len(open) != 3 {
		t.Fatalf("expected 3 open proposals, got %d", len(open))
	}
	// Newest first.
	if open[0].ID != third.ID || open[2].ID != first.ID {
		t.Fatalf("expected newest first, got %d, %d, %d", open[0].ID, open[1].ID, open[2].ID)
	}

	limited, err := s.ListProposalsByState(ctx, core.StateOpen, 2)
	if err != nil {
		t.Fatalf("list limited: %v", err)
	}
	if len(limited) != 2 || limited[0].ID != third.ID {
		t.Fatalf("unexpected limited list: %+v", limited)
	}

	if err := s.RejectProposal(ctx, second.ID); err != nil {
		t.Fatalf("reject: %v", err)
	}
	rejected, err := s.ListProposalsByState(ctx, core.StateRejected, 0)
	if err != nil {
		t.Fatalf("list rejected: %v", err)
	}
	if len(rejected) != 1 || rejected[0].ID != second.ID {
		t.Fatalf("unexpected rejected list: %+v", rejected)
	}
	if rejected[0].Resolved == nil {
		t.Fatal("a rejected proposal must carry a resolved timestamp")
	}
	if rejected[0].Approval != "" || rejected[0].MergedRev != "" {
		t.Fatalf("a rejection must not record approval or a merged rev: %+v", rejected[0])
	}
	merged, err := s.ListProposalsByState(ctx, core.StateMerged, 0)
	if err != nil {
		t.Fatalf("list merged: %v", err)
	}
	if len(merged) != 0 {
		t.Fatalf("expected no merged proposals, got %d", len(merged))
	}
}

func TestProposalTransitionsAreGuarded(t *testing.T) {
	s, _, cleanup := newTestStore(t)
	defer cleanup()
	ctx := context.Background()

	space := mkSpace(t, s, ctx, "bigbes", "rfcs")

	merged := mkProposal(t, s, ctx, space.ID, "to merge")
	if err := s.MarkProposalMerged(ctx, merged.ID, core.ApprovalHuman, "deadbeef"); err != nil {
		t.Fatalf("merge: %v", err)
	}
	got, err := s.GetProposal(ctx, merged.ID)
	if err != nil {
		t.Fatalf("get merged: %v", err)
	}
	if got.State != core.StateMerged || got.Approval != core.ApprovalHuman || got.MergedRev != "deadbeef" {
		t.Fatalf("unexpected merged proposal: %+v", got)
	}
	if got.Resolved == nil {
		t.Fatal("a merged proposal must carry a resolved timestamp")
	}

	// merged -> merged and merged -> rejected must both fail.
	if err := s.MarkProposalMerged(ctx, merged.ID, core.ApprovalHuman, "cafe"); !errors.Is(err, core.ErrInvalidTransition) {
		t.Fatalf("re-merge = %v, want ErrInvalidTransition", err)
	}
	if err := s.RejectProposal(ctx, merged.ID); !errors.Is(err, core.ErrInvalidTransition) {
		t.Fatalf("merged->rejected = %v, want ErrInvalidTransition", err)
	}
	// The row did not move.
	got, err = s.GetProposal(ctx, merged.ID)
	if err != nil {
		t.Fatalf("get merged: %v", err)
	}
	if got.State != core.StateMerged || got.MergedRev != "deadbeef" {
		t.Fatalf("illegal transition modified the row: %+v", got)
	}

	rejected := mkProposal(t, s, ctx, space.ID, "to reject")
	if err := s.RejectProposal(ctx, rejected.ID); err != nil {
		t.Fatalf("reject: %v", err)
	}
	if err := s.RejectProposal(ctx, rejected.ID); !errors.Is(err, core.ErrInvalidTransition) {
		t.Fatalf("re-reject = %v, want ErrInvalidTransition", err)
	}
	if err := s.MarkProposalMerged(ctx, rejected.ID, core.ApprovalPolicy, "cafe"); !errors.Is(err, core.ErrInvalidTransition) {
		t.Fatalf("rejected->merged = %v, want ErrInvalidTransition", err)
	}

	if err := s.RejectProposal(ctx, 99999); !errors.Is(err, ErrNotFound) {
		t.Fatalf("resolving a missing proposal = %v, want ErrNotFound", err)
	}
	if err := s.MarkProposalMerged(ctx, 99999, core.ApprovalHuman, "cafe"); !errors.Is(err, ErrNotFound) {
		t.Fatalf("merging a missing proposal = %v, want ErrNotFound", err)
	}
}

// TestMergeProposalIsAtomic is the reason the transaction exists: a merge that
// cannot re-point the registry must not leave the proposal reading merged.
func TestMergeProposalIsAtomic(t *testing.T) {
	s, _, cleanup := newTestStore(t)
	defer cleanup()
	ctx := context.Background()

	specs := mkSpace(t, s, ctx, "bigbes", "rfcs")
	notes := mkSpace(t, s, ctx, "bigbes", "notes")
	foreign := docID(t, "NOTE-1")
	if _, err := s.RegisterDocID(ctx, notes.ID, DocRef{ID: foreign, Path: "n.md"}, "rev1"); err != nil {
		t.Fatalf("register: %v", err)
	}

	p := mkProposal(t, s, ctx, specs.ID, "claims a foreign id")
	err := s.MergeProposal(ctx, Merge{
		ProposalID: p.ID,
		SpaceID:    specs.ID,
		Approval:   core.ApprovalHuman,
		MergedRev:  "deadbeef",
		Docs: []DocRef{
			{ID: docID(t, "SPEC-1"), Path: "a.md"},
			{ID: foreign, Path: "b.md"},
		},
	})
	if !errors.Is(err, ErrDocIDTaken) {
		t.Fatalf("merge with a colliding id = %v, want ErrDocIDTaken", err)
	}
	got, err := s.GetProposal(ctx, p.ID)
	if err != nil {
		t.Fatalf("get proposal: %v", err)
	}
	if got.State != core.StateOpen {
		t.Fatalf("failed merge left the proposal %s, want open", got.State)
	}
	// The whole batch rolled back, including the ID that would have applied.
	if _, err := s.DocByID(ctx, docID(t, "SPEC-1")); !errors.Is(err, ErrNotFound) {
		t.Fatalf("failed merge registered SPEC-1 anyway: %v", err)
	}

	// The same merge without the collision commits both halves.
	if err := s.MergeProposal(ctx, Merge{
		ProposalID: p.ID,
		SpaceID:    specs.ID,
		Approval:   core.ApprovalPolicy,
		MergedRev:  "deadbeef",
		Docs:       []DocRef{{ID: docID(t, "SPEC-1"), Path: "a.md"}},
	}); err != nil {
		t.Fatalf("merge: %v", err)
	}
	got, err = s.GetProposal(ctx, p.ID)
	if err != nil {
		t.Fatalf("get proposal: %v", err)
	}
	if got.State != core.StateMerged || got.Approval != core.ApprovalPolicy {
		t.Fatalf("unexpected merged proposal: %+v", got)
	}
	doc, err := s.DocByID(ctx, docID(t, "SPEC-1"))
	if err != nil {
		t.Fatalf("lookup after merge: %v", err)
	}
	if doc.SpaceID != specs.ID || doc.Path != "a.md" || doc.UpdatedRev != "deadbeef" {
		t.Fatalf("unexpected registry row after merge: %+v", doc)
	}
}

// TestProposalCheckConstraints proves the invariants hold against SQL that does
// not go through this package — a stray UPDATE cannot produce a merged row with
// no approval, or an unknown state.
func TestProposalCheckConstraints(t *testing.T) {
	s, pool, cleanup := newTestStore(t)
	defer cleanup()
	ctx := context.Background()

	space := mkSpace(t, s, ctx, "bigbes", "rfcs")
	p := mkProposal(t, s, ctx, space.ID, "constrained")

	for _, tc := range []struct {
		name string
		q    string
		args []any
	}{
		{"unknown state", `UPDATE proposal SET state = 'abandoned' WHERE id = $1`, []any{p.ID}},
		{"unknown approval", `UPDATE proposal SET approval = 'vibes' WHERE id = $1`, []any{p.ID}},
		{
			"merged without approval",
			`UPDATE proposal SET state = 'merged', merged_rev = 'abc', resolved = now() WHERE id = $1`,
			[]any{p.ID},
		},
		{
			"merged without a merged rev",
			`UPDATE proposal SET state = 'merged', approval = 'human', resolved = now() WHERE id = $1`,
			[]any{p.ID},
		},
		{
			"open but resolved",
			`UPDATE proposal SET resolved = now() WHERE id = $1`,
			[]any{p.ID},
		},
		{
			"approval on an open proposal",
			`UPDATE proposal SET approval = 'human' WHERE id = $1`,
			[]any{p.ID},
		},
		{
			"empty provenance",
			`UPDATE proposal SET agent = '' WHERE id = $1`,
			[]any{p.ID},
		},
	} {
		t.Run(tc.name, func(t *testing.T) {
			if _, err := pool.ExecContext(ctx, tc.q, tc.args...); err == nil {
				t.Fatalf("%s: expected a constraint violation, got none", tc.name)
			}
		})
	}
}