package protocol

import (
	"encoding/json"
	"testing"
)

// Golden wire frames as emitted by the Kotlin server (kotlinx.serialization). These
// strings are the cross-language contract: the Kotlin side pins the encode in
// ServerMessageSerializationTest; this test pins the Go decode of the exact same bytes,
// so a discriminator (@SerialName) or field-name drift fails loudly on one side.
func TestDecodeGoldenServerFrames(t *testing.T) {
	cases := []struct {
		name      string
		json      string
		wantType  string
		eventBear bool
		check     func(t *testing.T, m ServerMessage)
	}{
		{
			name:      "session.announced",
			json:      `{"type":"session.announced","sessionId":"s1","workflowId":"healthcheck","sequence":6,"sessionSequence":1}`,
			wantType:  TypeSessionAnnounced,
			eventBear: true,
			check: func(t *testing.T, m ServerMessage) {
				if m.SessionID != "s1" || m.WorkflowID != "healthcheck" {
					t.Fatalf("session.announced fields: %+v", m)
				}
			},
		},
		{
			name:      "chat.turn",
			json:      `{"type":"chat.turn","sessionId":"s1","turnId":"t9","role":"ROUTER","content":"hi there","sequence":7,"sessionSequence":2}`,
			wantType:  TypeChatTurn,
			eventBear: true,
			check: func(t *testing.T, m ServerMessage) {
				if m.Role != "ROUTER" || m.Content != "hi there" || m.TurnID != "t9" {
					t.Fatalf("chat.turn fields: %+v", m)
				}
			},
		},
		{
			name:      "stage.started",
			json:      `{"type":"stage.started","sessionId":"s1","stageId":"write_script","occurredAt":123,"sequence":8,"sessionSequence":3}`,
			wantType:  TypeStageStarted,
			eventBear: true,
			check: func(t *testing.T, m ServerMessage) {
				if m.StageID != "write_script" {
					t.Fatalf("stage.started fields: %+v", m)
				}
			},
		},
		{
			name:      "tool.completed",
			json:      `{"type":"tool.completed","sessionId":"s1","toolName":"shell","outputSummary":"ok","occurredAt":1,"diff":null,"sequence":9,"sessionSequence":4}`,
			wantType:  TypeToolCompleted,
			eventBear: true,
			check: func(t *testing.T, m ServerMessage) {
				if m.ToolName != "shell" || m.Summary != "ok" {
					t.Fatalf("tool.completed fields: %+v", m)
				}
			},
		},
		{
			// Plane-2 rationale (verified preconditions) must survive decode — it is the
			// justification shown in the approval band, not the opaque tier.
			name:      "approval.required carries plane-2 rationale",
			json:      `{"type":"approval.required","sessionId":"s1","requestId":"req-1","tier":"T3","riskSummary":{"level":"MEDIUM","factors":[],"recommendedAction":"PROMPT_USER","rationale":["[PATH_OUTSIDE_WORKSPACE] outside: /tmp/x"]},"toolName":"file_write","preview":"--- a/x\n+++ b/x","sequence":12,"sessionSequence":3}`,
			wantType:  TypeApprovalRequired,
			eventBear: true,
			check: func(t *testing.T, m ServerMessage) {
				if m.RiskSummary == nil {
					t.Fatalf("approval.required: riskSummary decoded nil")
				}
				if len(m.RiskSummary.Rationale) != 1 || m.RiskSummary.Rationale[0] != "[PATH_OUTSIDE_WORKSPACE] outside: /tmp/x" {
					t.Fatalf("rationale not decoded: %+v", m.RiskSummary)
				}
			},
		},
		{
			name:      "session.workspace_bound carries the cwd",
			json:      `{"type":"session.workspace_bound","sessionId":"s1","workspaceRoot":"/home/kami/Programs/correx","sequence":4,"sessionSequence":1}`,
			wantType:  TypeWorkspaceBound,
			eventBear: true,
			check: func(t *testing.T, m ServerMessage) {
				if m.WorkspaceRoot != "/home/kami/Programs/correx" {
					t.Fatalf("workspaceRoot not decoded: %+v", m)
				}
			},
		},
		{
			name:      "chat.turn carries router metrics",
			json:      `{"type":"chat.turn","sessionId":"s1","turnId":"t9","role":"ROUTER","content":"hi","latencyMs":3000,"totalTokens":943,"sequence":7,"sessionSequence":2}`,
			wantType:  TypeChatTurn,
			eventBear: true,
			check: func(t *testing.T, m ServerMessage) {
				if m.LatencyMs == nil || *m.LatencyMs != 3000 || m.TotalTokens == nil || *m.TotalTokens != 943 {
					t.Fatalf("chat.turn metrics: %+v", m)
				}
			},
		},
		{
			name:      "router.narration carries content + metrics",
			json:      `{"type":"router.narration","sessionId":"s1","content":"moving on","stageId":"validate","latencyMs":2000,"totalTokens":120,"sequence":10,"sessionSequence":5}`,
			wantType:  TypeRouterNarration,
			eventBear: true,
			check: func(t *testing.T, m ServerMessage) {
				if m.Content != "moving on" || m.LatencyMs == nil || *m.LatencyMs != 2000 || m.TotalTokens == nil || *m.TotalTokens != 120 {
					t.Fatalf("router.narration: %+v", m)
				}
			},
		},
		{
			name:      "snapshot_complete (non-event control frame)",
			json:      `{"type":"snapshot_complete"}`,
			wantType:  TypeSnapshotComplete,
			eventBear: false,
		},
		{
			name: "session.stats carries nested derived metrics",
			json: `{"type":"session.stats","sessionId":"s1","stats":{"sessionId":"s1","eventCount":12,` +
				`"sessionDurationMs":60000,"inferenceCount":3,"inferenceMs":6000,"promptTokens":310,` +
				`"completionTokens":170,"tokensPerSecond":28.3,` +
				`"perProvider":[{"provider":"lfm:a","completedCount":2,"totalLatencyMs":5000,` +
				`"promptTokens":300,"completionTokens":150,"tokensPerSecond":30.0}],` +
				`"toolCount":3,"toolMs":1500,"perTool":[{"toolName":"shell.read","completedCount":2,"totalDurationMs":1200}],` +
				`"approvalsRequested":2,"approvalsResolved":1,"approvalsPending":1,"approvalWaitMs":30000,` +
				`"avgApprovalWaitMs":30000,"perTier":[{"tier":"T2","requestedCount":2,"resolvedCount":1,` +
				`"totalWaitMs":30000,"avgWaitMs":30000}],` +
				`"failures":{"inferenceFailures":1,"inferenceTimeouts":0,"toolFailures":1,"toolRejections":0,` +
				`"stageFailures":0,"workflowFailures":1},"inferencePct":10.0,"toolPct":2.5,"approvalWaitPct":50.0}}`,
			wantType:  TypeSessionStats,
			eventBear: false,
			check: func(t *testing.T, m ServerMessage) {
				if m.SessionID != "s1" {
					t.Fatalf("session.stats sessionId: %+v", m)
				}
				if m.Stats == nil {
					t.Fatalf("session.stats: Stats is nil")
				}
				if m.Stats.InferenceCount != 3 || m.Stats.CompletionTokens != 170 {
					t.Fatalf("session.stats inference totals: %+v", m.Stats)
				}
				if len(m.Stats.PerProvider) != 1 || m.Stats.PerProvider[0].Provider != "lfm:a" {
					t.Fatalf("session.stats perProvider: %+v", m.Stats.PerProvider)
				}
				if m.Stats.Failures.WorkflowFailures != 1 || m.Stats.ApprovalWaitPct != 50.0 {
					t.Fatalf("session.stats failures/pct: %+v", m.Stats)
				}
			},
		},
		{
			name: "idea.list carries the cross-session board",
			json: `{"type":"idea.list","ideas":[{"ideaId":"i1","text":"cache the repo map","capturedAtMs":1000},` +
				`{"ideaId":"i2","text":"add --dry-run","capturedAtMs":2000}]}`,
			wantType:  TypeIdeaList,
			eventBear: false,
			check: func(t *testing.T, m ServerMessage) {
				if len(m.Ideas) != 2 {
					t.Fatalf("idea.list ideas: %+v", m.Ideas)
				}
				if m.Ideas[0].IdeaID != "i1" || m.Ideas[0].Text != "cache the repo map" || m.Ideas[0].CapturedAtMs != 1000 {
					t.Fatalf("idea.list idea[0]: %+v", m.Ideas[0])
				}
			},
		},
		{
			name: "health.checks carries nested health report",
			json: `{"type":"health.checks","health":{"overall":"DEGRADED","subjects":[` +
				`{"subject":"DISK","status":"DEGRADED","metric":"free_bytes","observedValue":512000000,` +
				`"detail":"disk free below 1 GB threshold","since":"2026-06-14T10:00:00Z"},` +
				`{"subject":"EVENT_STORE","status":"HEALTHY","metric":"write_latency_ms","observedValue":4,` +
				`"detail":"ok","since":"2026-06-14T09:00:00Z"}],` +
				`"checkedAt":"2026-06-14T10:05:00Z"}}`,
			wantType:  TypeHealthChecks,
			eventBear: false,
			check: func(t *testing.T, m ServerMessage) {
				if m.Health == nil {
					t.Fatalf("health.checks: Health is nil")
				}
				if m.Health.Overall != "DEGRADED" {
					t.Fatalf("health.checks overall = %q, want DEGRADED", m.Health.Overall)
				}
				if len(m.Health.Subjects) != 2 {
					t.Fatalf("health.checks subjects len = %d, want 2", len(m.Health.Subjects))
				}
				disk := m.Health.Subjects[0]
				if disk.Subject != "DISK" || disk.Status != "DEGRADED" || disk.ObservedValue != 512000000 {
					t.Fatalf("health.checks DISK subject: %+v", disk)
				}
				es := m.Health.Subjects[1]
				if es.Subject != "EVENT_STORE" || es.Status != "HEALTHY" {
					t.Fatalf("health.checks EVENT_STORE subject: %+v", es)
				}
				if m.Health.CheckedAt != "2026-06-14T10:05:00Z" {
					t.Fatalf("health.checks checkedAt = %q", m.Health.CheckedAt)
				}
			},
		},
		{
			name: "workflow.proposed carries candidate workflows",
			json: `{"type":"workflow.proposed","sessionId":"s1","proposalId":"prop-1","prompt":"Run one?",` +
				`"candidates":[{"workflowId":"research","reason":"gather + report"},{"workflowId":"role_pipeline","reason":""}],` +
				`"originalRequest":"find papers","sequence":9,"sessionSequence":4}`,
			wantType:  TypeWorkflowProposed,
			eventBear: true,
			check: func(t *testing.T, m ServerMessage) {
				if m.ProposalID != "prop-1" || m.Prompt != "Run one?" || m.OriginalRequest != "find papers" {
					t.Fatalf("workflow.proposed fields: %+v", m)
				}
				if len(m.Candidates) != 2 {
					t.Fatalf("workflow.proposed candidates: %+v", m.Candidates)
				}
				if m.Candidates[0].WorkflowID != "research" || m.Candidates[0].Reason != "gather + report" {
					t.Fatalf("workflow.proposed candidate[0]: %+v", m.Candidates[0])
				}
			},
		},
		{
			name: "clarification.required carries structured questions",
			json: `{"type":"clarification.required","sessionId":"s1","requestId":"req-1","stageId":"analyst",` +
				`"questions":[{"id":"stack","prompt":"Which stack?","options":["React","Vue"],"multiSelect":false,"header":"Stack"}],` +
				`"sequence":9,"sessionSequence":4}`,
			wantType:  TypeClarification,
			eventBear: true,
			check: func(t *testing.T, m ServerMessage) {
				if m.RequestID != "req-1" || m.StageID != "analyst" {
					t.Fatalf("clarification ids: %+v", m)
				}
				if len(m.Questions) != 1 {
					t.Fatalf("clarification questions: %+v", m.Questions)
				}
				q := m.Questions[0]
				if q.Prompt != "Which stack?" || q.Header != "Stack" ||
					len(q.Options) != 2 || q.Options[0] != "React" {
					t.Fatalf("clarification question fields: %+v", q)
				}
			},
		},
	}

	for _, c := range cases {
		t.Run(c.name, func(t *testing.T) {
			m, err := Decode([]byte(c.json))
			if err != nil {
				t.Fatalf("decode failed: %v", err)
			}
			if m.Type != c.wantType {
				t.Fatalf("type = %q, want %q", m.Type, c.wantType)
			}
			if m.IsEventBearing() != c.eventBear {
				t.Fatalf("IsEventBearing = %v, want %v", m.IsEventBearing(), c.eventBear)
			}
			if c.check != nil {
				c.check(t, m)
			}
		})
	}
}

// TestEncodeGoldenClientFrames pins the Go→Kotlin wire format for client messages.
// The discriminator is the fully-qualified Kotlin class name (kotlinx default for
// sealed classes without @SerialName), keyed under "type". These bytes must be
// accepted verbatim by the Kotlin server's ProtocolSerializer / Json decoder.
func TestEncodeGoldenClientFrames(t *testing.T) {
	cases := []struct {
		name     string
		frame    []byte
		wantType string
		check    func(t *testing.T, raw map[string]any)
	}{
		{
			// Hello is the first frame on every (re)connect — carries the client cwd so
			// the server can bind a workspace before any session starts.
			name:     "Hello carries workingDir",
			frame:    Hello("/home/kami/Projects/correx"),
			wantType: clientPrefix + "Hello",
			check: func(t *testing.T, raw map[string]any) {
				if raw["workingDir"] != "/home/kami/Projects/correx" {
					t.Fatalf("Hello workingDir = %v", raw["workingDir"])
				}
			},
		},
		{
			name:     "GetHealthChecks encodes correctly",
			frame:    GetHealthChecks(),
			wantType: clientPrefix + "GetHealthChecks",
		},
		{
			name:     "DiscardIdea carries the ideaId",
			frame:    DiscardIdea("i1"),
			wantType: clientPrefix + "DiscardIdea",
			check: func(t *testing.T, raw map[string]any) {
				if raw["ideaId"] != "i1" {
					t.Fatalf("DiscardIdea ideaId: %+v", raw)
				}
			},
		},
		{
			name: "ClarificationResponse carries ids + answers",
			frame: ClarificationResponse("s1", "analyst", "req-1",
				[]ClarificationAnswerDto{{QuestionID: "stack", Value: "React"}}),
			wantType: clientPrefix + "ClarificationResponse",
			check: func(t *testing.T, raw map[string]any) {
				if raw["sessionId"] != "s1" || raw["stageId"] != "analyst" || raw["requestId"] != "req-1" {
					t.Fatalf("ClarificationResponse ids: %+v", raw)
				}
				answers, ok := raw["answers"].([]any)
				if !ok || len(answers) != 1 {
					t.Fatalf("ClarificationResponse answers: %+v", raw["answers"])
				}
				a := answers[0].(map[string]any)
				if a["questionId"] != "stack" || a["value"] != "React" {
					t.Fatalf("ClarificationResponse answer: %+v", a)
				}
			},
		},
	}

	for _, c := range cases {
		t.Run(c.name, func(t *testing.T) {
			var raw map[string]any
			if err := json.Unmarshal(c.frame, &raw); err != nil {
				t.Fatalf("unmarshal failed: %v", err)
			}
			if raw["type"] != c.wantType {
				t.Fatalf("type = %q, want %q", raw["type"], c.wantType)
			}
			if c.check != nil {
				c.check(t, raw)
			}
		})
	}
}