package tools_test

import (
	"context"
	"encoding/json"
	"fmt"
	"strings"
	"testing"

	"github.com/krow/krow-backend/go-api/internal/authctx"
	"github.com/krow/krow-backend/go-api/internal/testutil"
	"github.com/krow/krow-backend/go-api/internal/tools"
)

// The second write tool.
//
// Half of what is asserted here is the same as assign_worker's, and that is the
// point rather than duplication: the confirmation gate was built once, and a
// second tool that has to re-earn "cannot write without approval" would mean it
// had been special-cased into the first. It is not — this tool declares an
// effect and a renderer, and everything else comes from the registry.
//
// The other half is this tool's own: a funnel has an order, terminal outcomes
// are different from steps along it, and moving somebody backwards is not a
// move at all.

type funnelFixture struct {
	orgID  string
	admin  authctx.Identity
	talent authctx.Identity
	appID  string
	name   string
}

func seedFunnel(t *testing.T, h *testutil.Harness, slug string) funnelFixture {
	t.Helper()
	ctx := context.Background()
	org := freshOrg(t, h, slug)

	f := funnelFixture{orgID: org, name: "Dana Okonkwo"}
	f.admin = authctx.Identity{
		UserID: seedUser(t, h, org, fmt.Sprintf("boss-%s@example.test", slug), "admin"),
		OrgID:  org, Role: "admin", Email: fmt.Sprintf("boss-%s@example.test", slug),
	}
	candidateEmail := fmt.Sprintf("dana-%s@example.test", slug)
	f.talent = authctx.Identity{
		UserID: seedUser(t, h, org, candidateEmail, "talent"),
		OrgID:  org, Role: "talent", Email: candidateEmail,
	}

	var postingID string
	if err := h.Pool.QueryRow(ctx, `
		INSERT INTO job_postings (org_id, title, status, headcount)
		VALUES ($1::uuid, 'Sous Chef', 'active', 1) RETURNING id::text`, org).Scan(&postingID); err != nil {
		t.Fatalf("seed posting: %v", err)
	}
	if err := h.Pool.QueryRow(ctx, `
		INSERT INTO job_applications (org_id, job_posting_id, applicant_name, email, status, ai_score)
		VALUES ($1::uuid, $2::uuid, $3, $4, 'ai_screened', 88) RETURNING id::text`,
		org, postingID, f.name, candidateEmail).Scan(&f.appID); err != nil {
		t.Fatalf("seed application: %v", err)
	}
	return f
}

func stageOf(t *testing.T, h *testutil.Harness, appID string) string {
	t.Helper()
	var s string
	if err := h.Pool.QueryRow(context.Background(),
		`SELECT status::text FROM job_applications WHERE id = $1::uuid`, appID).Scan(&s); err != nil {
		t.Fatalf("read stage: %v", err)
	}
	return s
}

func moveArgs(appID, stage string) string {
	return fmt.Sprintf(`{"application_id":%q,"stage":%q}`, appID, stage)
}

/* ── The gate, again ────────────────────────────────────────────────────── */

func TestMovingACandidateNeedsApproval(t *testing.T) {
	h := testutil.New(t)
	f := seedFunnel(t, h, "funnel-gate")
	reg := liveRegistry(t, h)
	tc := tools.Context{Principal: f.admin, RunID: "run_m1"}
	args := moveArgs(f.appID, "interview")

	res := reg.Dispatch(context.Background(), tc, "move_application", json.RawMessage(args))
	if res.Confirmation == nil {
		t.Fatalf("expected a confirmation, got %+v", res)
	}
	if got := stageOf(t, h, f.appID); got != "ai_screened" {
		t.Fatalf("the candidate moved to %q before anyone approved anything", got)
	}

	// Names and readable stages, not enum values and uuids.
	body, _ := json.Marshal(res.Confirmation)
	for _, want := range []string{"Dana Okonkwo", "Sous Chef", "Interview"} {
		if !strings.Contains(string(body), want) {
			t.Errorf("the confirmation does not mention %q: %s", want, body)
		}
	}
	if strings.Contains(res.Confirmation.Title, "ai_screened") {
		t.Error("the confirmation shows an enum value where it should show a label")
	}

	tc.Confirmation = res.Confirmation.Token
	if out := reg.Dispatch(context.Background(), tc, "move_application", json.RawMessage(args)); out.Error != nil {
		t.Fatalf("an approved move should run: %+v", out.Error)
	}
	if got := stageOf(t, h, f.appID); got != "interview" {
		t.Fatalf("stage is %q after approval, want interview", got)
	}
}

func TestACandidateCannotMoveThemselves(t *testing.T) {
	// `job-applications` lists to everyone — a talent caller may read their own
	// — and updates for operators only. Asking the policy the READ question
	// here would let a candidate advance themselves to interview.
	h := testutil.New(t)
	f := seedFunnel(t, h, "funnel-self")
	reg := liveRegistry(t, h)

	res := reg.Dispatch(context.Background(),
		tools.Context{Principal: f.talent, RunID: "run_m2"},
		"move_application", json.RawMessage(moveArgs(f.appID, "interview")))

	if res.Confirmation != nil {
		t.Fatal("a candidate was asked to approve their own advancement")
	}
	if res.Error == nil || res.Error.Code != tools.CodeDenied {
		t.Fatalf("want the standard denial, got %+v", res.Error)
	}
	if got := stageOf(t, h, f.appID); got != "ai_screened" {
		t.Fatalf("a candidate moved themselves to %q", got)
	}
}

func TestAnotherTenantsCandidateIsAbsentRatherThanForbidden(t *testing.T) {
	h := testutil.New(t)
	mine := seedFunnel(t, h, "funnel-mine")
	theirs := seedFunnel(t, h, "funnel-theirs")
	reg := liveRegistry(t, h)
	tc := tools.Context{Principal: mine.admin, RunID: "run_m3"}

	real := reg.Dispatch(context.Background(), tc, "move_application",
		json.RawMessage(moveArgs(theirs.appID, "interview")))
	fake := reg.Dispatch(context.Background(), tc, "move_application",
		json.RawMessage(moveArgs("00000000-0000-0000-0000-0000000000ff", "interview")))

	if real.Error == nil || fake.Error == nil {
		t.Fatal("a cross-tenant or invented application id was accepted")
	}
	if real.Error.Code != fake.Error.Code || real.Error.Message != fake.Error.Message {
		t.Errorf("a real-but-forbidden candidate is distinguishable from an imaginary one:\n"+
			"  other tenant: %s\n  invented:     %s", real.Error.Message, fake.Error.Message)
	}
	if got := stageOf(t, h, theirs.appID); got != "ai_screened" {
		t.Fatal("a write crossed a tenant boundary")
	}
}

/* ── The funnel's own rules ─────────────────────────────────────────────── */

func TestATerminalOutcomeIsWarnedAbout(t *testing.T) {
	// Hiring and rejecting are the hardest decisions to walk back, and a model
	// reaching them early is the most expensive mistake available here. They
	// get a warning above the button, not a footnote.
	h := testutil.New(t)
	f := seedFunnel(t, h, "funnel-terminal")
	reg := liveRegistry(t, h)

	for stage, word := range map[string]string{"hired": "final outcome", "rejected": "final outcome"} {
		res := reg.Dispatch(context.Background(),
			tools.Context{Principal: f.admin, RunID: "run_m4"},
			"move_application", json.RawMessage(moveArgs(f.appID, stage)))
		if res.Confirmation == nil {
			t.Fatalf("%s: expected a confirmation, got %+v", stage, res)
		}
		var found bool
		for _, w := range res.Confirmation.Warnings {
			if strings.Contains(w, word) {
				found = true
			}
		}
		if !found {
			t.Errorf("moving to %s was described without warning it is final: %v",
				stage, res.Confirmation.Warnings)
		}
	}
}

func TestSkippingStagesIsWarnedAbout(t *testing.T) {
	// Legitimate — a strong candidate can go straight to interview — but a
	// model misreading which stage somebody is at produces exactly this shape,
	// so the person approving should be told.
	h := testutil.New(t)
	f := seedFunnel(t, h, "funnel-skip")
	reg := liveRegistry(t, h)

	// ai_screened → interview skips shortlisted.
	res := reg.Dispatch(context.Background(),
		tools.Context{Principal: f.admin, RunID: "run_m5"},
		"move_application", json.RawMessage(moveArgs(f.appID, "interview")))
	if res.Confirmation == nil {
		t.Fatalf("expected a confirmation, got %+v", res)
	}
	var found bool
	for _, w := range res.Confirmation.Warnings {
		if strings.Contains(w, "skips") {
			found = true
		}
	}
	if !found {
		t.Errorf("skipping a stage was not mentioned: %v", res.Confirmation.Warnings)
	}
}

func TestACandidateCannotBeMovedBackToApplied(t *testing.T) {
	// Not a funnel action but an undo — and one that would erase the record of
	// having been screened. Refused as invalid input rather than described.
	h := testutil.New(t)
	f := seedFunnel(t, h, "funnel-back")
	reg := liveRegistry(t, h)

	res := reg.Dispatch(context.Background(),
		tools.Context{Principal: f.admin, RunID: "run_m6"},
		"move_application", json.RawMessage(moveArgs(f.appID, "applied")))

	if res.Confirmation != nil {
		t.Fatal("moving a candidate backwards was offered for approval")
	}
	if res.Error == nil || res.Error.Code != tools.CodeInvalidInput {
		t.Fatalf("want invalid input, got %+v", res.Error)
	}
}

func TestMovingSomebodyToWhereTheyAlreadyAreChangesNothing(t *testing.T) {
	h := testutil.New(t)
	f := seedFunnel(t, h, "funnel-noop")
	reg := liveRegistry(t, h)
	tc := tools.Context{Principal: f.admin, RunID: "run_m7"}
	args := moveArgs(f.appID, "ai_screened")

	res := reg.Dispatch(context.Background(), tc, "move_application", json.RawMessage(args))
	if res.Confirmation == nil {
		t.Fatalf("expected a confirmation, got %+v", res)
	}
	// Said out loud rather than silently doing nothing.
	var warned bool
	for _, w := range res.Confirmation.Warnings {
		if strings.Contains(w, "changes nothing") {
			warned = true
		}
	}
	if !warned {
		t.Errorf("a no-op move was not flagged as one: %v", res.Confirmation.Warnings)
	}

	tc.Confirmation = res.Confirmation.Token
	out := reg.Dispatch(context.Background(), tc, "move_application", json.RawMessage(args))
	if out.Error != nil {
		t.Fatalf("a no-op move should succeed: %+v", out.Error)
	}
	body, _ := json.Marshal(out.Data)
	if !strings.Contains(string(body), `"changed":false`) {
		t.Errorf("a no-op did not report itself as one: %s", body)
	}
}

/* ── The lookup ─────────────────────────────────────────────────────────── */

func TestCandidatesAwaitingReturnsIdsAndReadableStages(t *testing.T) {
	// §4: a tool that requires the model to guess an id is a design bug. This
	// is the lookup that makes move_application usable without guessing.
	h := testutil.New(t)
	f := seedFunnel(t, h, "funnel-lookup")
	reg := liveRegistry(t, h)

	res := reg.Dispatch(context.Background(),
		tools.Context{Principal: f.admin, RunID: "run_m8"},
		"candidates_awaiting", json.RawMessage(`{}`))
	if res.Error != nil {
		t.Fatalf("candidates_awaiting failed: %+v", res.Error)
	}
	body, _ := json.Marshal(res.Data)
	for _, want := range []string{f.appID, "Dana Okonkwo", "Screened", "matchScore"} {
		if !strings.Contains(string(body), want) {
			t.Errorf("the lookup does not carry %q: %s", want, body)
		}
	}
}

func TestCandidatesAwaitingExcludesSettledCandidates(t *testing.T) {
	// "Still in the running" is the useful default: a person asking who is
	// waiting does not mean the people already hired or rejected.
	h := testutil.New(t)
	f := seedFunnel(t, h, "funnel-settled")
	reg := liveRegistry(t, h)
	tc := tools.Context{Principal: f.admin, RunID: "run_m9"}

	if _, err := h.Pool.Exec(context.Background(),
		`UPDATE job_applications SET status = 'rejected' WHERE id = $1::uuid`, f.appID); err != nil {
		t.Fatalf("settle: %v", err)
	}

	res := reg.Dispatch(context.Background(), tc, "candidates_awaiting", json.RawMessage(`{}`))
	if body, _ := json.Marshal(res.Data); strings.Contains(string(body), f.appID) {
		t.Errorf("a rejected candidate was listed as still in the running: %s", body)
	}

	// But asked for explicitly, they are there.
	res = reg.Dispatch(context.Background(), tc, "candidates_awaiting", json.RawMessage(`{"stage":"rejected"}`))
	if body, _ := json.Marshal(res.Data); !strings.Contains(string(body), f.appID) {
		t.Errorf("asking for rejected candidates did not return one: %s", body)
	}
}

func TestScreenedIsDerivedFromStageNotFromAVestigialColumn(t *testing.T) {
	// A live run reported five candidates sitting at the Screened stage all
	// carrying screened:false, and read it as the stage label running ahead of
	// the work. The data was fine; the tool was wrong. `screened` was read from
	// job_applications.screened_at, a column migration 000003 established that
	// nothing in the product ever writes — so it was null for every real row and
	// the flag was false for everyone, forever. The product's own definition,
	// in eight places, is status = 'applied'. This asserts that definition.
	//
	// The old test fixture hid this by inserting screened_at itself, which no
	// production path does; the seed below deliberately does not.
	h := testutil.New(t)
	f := seedFunnel(t, h, "funnel-screened")
	reg := liveRegistry(t, h)
	ctx := context.Background()

	var freshID string
	if err := h.Pool.QueryRow(ctx, `
		INSERT INTO job_applications (org_id, job_posting_id, applicant_name, email, status, ai_score)
		SELECT org_id, job_posting_id, 'Ivo Brandt', 'ivo-screened@example.test', 'applied', 0
		  FROM job_applications WHERE id = $1::uuid
		RETURNING id::text`, f.appID).Scan(&freshID); err != nil {
		t.Fatalf("seed applied candidate: %v", err)
	}

	res := reg.Dispatch(ctx,
		tools.Context{Principal: f.admin, RunID: "run_m10"},
		"candidates_awaiting", json.RawMessage(`{}`))
	if res.Error != nil {
		t.Fatalf("candidates_awaiting failed: %+v", res.Error)
	}

	var payload struct {
		Candidates []struct {
			ID       string `json:"applicationId"`
			Screened bool   `json:"screened"`
		} `json:"candidates"`
	}
	body, _ := json.Marshal(res.Data)
	if err := json.Unmarshal(body, &payload); err != nil {
		t.Fatalf("decode %s: %v", body, err)
	}

	seen := map[string]bool{}
	for _, c := range payload.Candidates {
		seen[c.ID] = c.Screened
	}
	if got, ok := seen[f.appID]; !ok {
		t.Fatalf("the ai_screened candidate was not returned: %s", body)
	} else if !got {
		t.Errorf("a candidate at the Screened stage reported screened:false — " +
			"the flag is being read from something other than the stage")
	}
	if got, ok := seen[freshID]; !ok {
		t.Fatalf("the applied candidate was not returned: %s", body)
	} else if got {
		t.Errorf("a candidate still at Applied reported screened:true")
	}
}

func TestMovingACandidateDoesNotWriteTheVestigialColumn(t *testing.T) {
	// Keeping this tool as the sole writer of screened_at would quietly redefine
	// the column to mean "an agent touched this row". status carries the stage
	// and the trajectory carries the who and when.
	h := testutil.New(t)
	f := seedFunnel(t, h, "funnel-vestigial")
	reg := liveRegistry(t, h)
	ctx := context.Background()
	tc := tools.Context{Principal: f.admin, RunID: "run_m11"}
	args := moveArgs(f.appID, "interview")

	res := reg.Dispatch(ctx, tc, "move_application", json.RawMessage(args))
	if res.Confirmation == nil {
		t.Fatalf("expected a confirmation, got %+v", res)
	}
	out, ok := reg.DispatchApproved(ctx, tc, res.Confirmation.Token)
	if !ok {
		t.Fatal("a valid token could not be redeemed")
	}
	if out.Result.Error != nil {
		t.Fatalf("approved move failed: %+v", out.Result.Error)
	}
	if got := stageOf(t, h, f.appID); got != "interview" {
		t.Fatalf("the approved move did not land: stage is %q", got)
	}

	var written bool
	if err := h.Pool.QueryRow(ctx,
		`SELECT screened_at IS NOT NULL FROM job_applications WHERE id = $1::uuid`,
		f.appID).Scan(&written); err != nil {
		t.Fatalf("read screened_at: %v", err)
	}
	if written {
		t.Errorf("move_application wrote screened_at, making it the column's only writer")
	}
}

// A candidate placed on a shift is not waiting on a decision. `assigned` is in
// the application_status enum but was in neither of this file's stage lists, so
// the "still in the running" predicate — written as NOT IN ('hired','rejected')
// — let them through, and candidates_awaiting listed somebody already working
// as somebody to chase. The same omission on the frontend dropped `assigned`
// out of every funnel bucket; here it fell into the wrong one instead.
func TestAnAssignedCandidateIsNotStillInTheRunning(t *testing.T) {
	h := testutil.New(t)
	f := seedFunnel(t, h, "funnel-assigned")
	reg := liveRegistry(t, h)
	ctx := context.Background()
	tc := tools.Context{Principal: f.admin, RunID: "run_m12"}

	if _, err := h.Pool.Exec(ctx,
		`UPDATE job_applications SET status = 'assigned' WHERE id = $1::uuid`, f.appID); err != nil {
		t.Fatalf("assign: %v", err)
	}

	res := reg.Dispatch(ctx, tc, "candidates_awaiting", json.RawMessage(`{}`))
	if res.Error != nil {
		t.Fatalf("candidates_awaiting failed: %+v", res.Error)
	}
	if body, _ := json.Marshal(res.Data); strings.Contains(string(body), f.appID) {
		t.Errorf("a candidate already assigned to a shift was listed as awaiting a decision: %s", body)
	}

	// Asked for by name they are there — the read tool can show every status,
	// even the one move_application is not allowed to set.
	res = reg.Dispatch(ctx, tc, "candidates_awaiting", json.RawMessage(`{"stage":"assigned"}`))
	if res.Error != nil {
		t.Fatalf("listing assigned candidates failed: %+v", res.Error)
	}
	body, _ := json.Marshal(res.Data)
	if !strings.Contains(string(body), f.appID) {
		t.Errorf("asking for assigned candidates did not return one: %s", body)
	}
	if !strings.Contains(string(body), "Assigned") {
		t.Errorf("the stage label is not readable: %s", body)
	}
}

// move_application must still refuse to *set* assigned: that state means an
// assignment row exists, and this tool writes none.
func TestMoveApplicationStillRefusesToSetAssigned(t *testing.T) {
	h := testutil.New(t)
	f := seedFunnel(t, h, "funnel-noassign")
	reg := liveRegistry(t, h)

	res := reg.Dispatch(context.Background(),
		tools.Context{Principal: f.admin, RunID: "run_m13"},
		"move_application", json.RawMessage(moveArgs(f.appID, "assigned")))
	if res.Error == nil {
		t.Fatalf("move_application accepted 'assigned'; it would mark a candidate assigned to nothing: %+v", res)
	}
	if res.Confirmation != nil {
		t.Errorf("it even offered a confirmation for it")
	}
}