package anthropic

import (
	"context"
	"encoding/json"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"
	"time"

	"github.com/thepeterstone/claudomator/internal/provider"
	"github.com/thepeterstone/claudomator/internal/retry"
)

// fakeAnthropicServer replies to POST /v1/messages with the given status and
// raw JSON body, capturing the last decoded request for assertions. Modeled
// on the fake OpenAI-compatible server pattern used in
// internal/llm/client_test.go and internal/executor/nativerunner_test.go
// (fakeChatServer), adapted to the Anthropic Messages API wire shape.
func fakeAnthropicServer(t *testing.T, status int, body string, capture *wireRequest) *httptest.Server {
	t.Helper()
	return httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if r.URL.Path != "/v1/messages" {
			t.Errorf("unexpected path %q", r.URL.Path)
		}
		if r.Header.Get("x-api-key") != "test-key" {
			t.Errorf("missing/wrong x-api-key header: %q", r.Header.Get("x-api-key"))
		}
		if r.Header.Get("anthropic-version") != APIVersion {
			t.Errorf("missing/wrong anthropic-version header: %q", r.Header.Get("anthropic-version"))
		}
		if r.Header.Get("content-type") != "application/json" {
			t.Errorf("missing/wrong content-type header: %q", r.Header.Get("content-type"))
		}
		if capture != nil {
			if err := json.NewDecoder(r.Body).Decode(capture); err != nil {
				t.Fatalf("decode request body: %v", err)
			}
		}
		w.Header().Set("Content-Type", "application/json")
		w.WriteHeader(status)
		w.Write([]byte(body))
	}))
}

func newTestProvider(url string) *Provider {
	return New("test-key", url, 5*time.Second)
}

// TestChat_PlainTextResponse covers a plain assistant text reply: no tool
// calls, stop_reason "end_turn", usage translated to provider.Usage with a
// non-zero CostUSD computed from the pricing table.
func TestChat_PlainTextResponse(t *testing.T) {
	var got wireRequest
	srv := fakeAnthropicServer(t, http.StatusOK, `{
		"id": "msg_1",
		"type": "message",
		"role": "assistant",
		"model": "claude-sonnet-5",
		"content": [{"type": "text", "text": "Hello there!"}],
		"stop_reason": "end_turn",
		"usage": {"input_tokens": 10, "output_tokens": 5}
	}`, &got)
	defer srv.Close()

	p := newTestProvider(srv.URL)
	resp, err := p.Chat(context.Background(), provider.ChatRequest{
		Model:  "claude-sonnet-5",
		System: "You are helpful.",
		Messages: []provider.Message{
			{Role: "user", Text: "hi"},
		},
	})
	if err != nil {
		t.Fatalf("Chat: %v", err)
	}
	if resp.Text != "Hello there!" {
		t.Errorf("Text: want %q got %q", "Hello there!", resp.Text)
	}
	if len(resp.ToolCalls) != 0 {
		t.Errorf("expected no tool calls, got %+v", resp.ToolCalls)
	}
	if resp.StopReason != "end_turn" {
		t.Errorf("StopReason: want end_turn got %q", resp.StopReason)
	}
	if resp.Usage.InputTokens != 10 || resp.Usage.OutputTokens != 5 {
		t.Errorf("usage tokens: got %+v", resp.Usage)
	}
	wantCost := float64(10)/1_000_000*3.00 + float64(5)/1_000_000*15.00
	if resp.Usage.CostUSD != wantCost {
		t.Errorf("CostUSD: want %v got %v", wantCost, resp.Usage.CostUSD)
	}

	// Verify the outgoing request shape: system is top-level, not a message.
	if got.System != "You are helpful." {
		t.Errorf("system: want %q got %q", "You are helpful.", got.System)
	}
	if len(got.Messages) != 1 || got.Messages[0].Role != "user" {
		t.Fatalf("messages: %+v", got.Messages)
	}
	if len(got.Messages[0].Content) != 1 || got.Messages[0].Content[0].Type != "text" || got.Messages[0].Content[0].Text != "hi" {
		t.Errorf("user content block: %+v", got.Messages[0].Content)
	}
	if got.MaxTokens != defaultMaxTokens {
		t.Errorf("max_tokens should default to %d, got %d", defaultMaxTokens, got.MaxTokens)
	}
}

// TestChat_ToolUseResponse verifies that a response whose content mixes a
// text block and a tool_use block round-trips into ChatResponse.ToolCalls
// correctly (id/name/args), and that tools declared on the request are
// translated to Anthropic's {name, description, input_schema} shape.
func TestChat_ToolUseResponse(t *testing.T) {
	var got wireRequest
	srv := fakeAnthropicServer(t, http.StatusOK, `{
		"id": "msg_2",
		"type": "message",
		"role": "assistant",
		"model": "claude-opus-4-8",
		"content": [
			{"type": "text", "text": "Let me check that."},
			{"type": "tool_use", "id": "toolu_01", "name": "read_file", "input": {"path": "a.txt"}}
		],
		"stop_reason": "tool_use",
		"usage": {"input_tokens": 20, "output_tokens": 8}
	}`, &got)
	defer srv.Close()

	p := newTestProvider(srv.URL)
	resp, err := p.Chat(context.Background(), provider.ChatRequest{
		Model:    "claude-opus-4-8",
		Messages: []provider.Message{{Role: "user", Text: "read a.txt"}},
		Tools: []provider.ToolSpec{
			{
				Name:        "read_file",
				Description: "Read a file.",
				ParametersJSONSchema: map[string]any{
					"type":       "object",
					"properties": map[string]any{"path": map[string]any{"type": "string"}},
					"required":   []string{"path"},
				},
			},
		},
	})
	if err != nil {
		t.Fatalf("Chat: %v", err)
	}
	if resp.Text != "Let me check that." {
		t.Errorf("Text: got %q", resp.Text)
	}
	if resp.StopReason != "tool_use" {
		t.Errorf("StopReason: want tool_use got %q", resp.StopReason)
	}
	if len(resp.ToolCalls) != 1 {
		t.Fatalf("expected 1 tool call, got %d: %+v", len(resp.ToolCalls), resp.ToolCalls)
	}
	tc := resp.ToolCalls[0]
	if tc.ID != "toolu_01" || tc.Name != "read_file" {
		t.Errorf("tool call id/name: got %+v", tc)
	}
	var args struct {
		Path string `json:"path"`
	}
	if err := json.Unmarshal([]byte(tc.ArgsJSON), &args); err != nil {
		t.Fatalf("tool call args not valid JSON: %v (%q)", err, tc.ArgsJSON)
	}
	if args.Path != "a.txt" {
		t.Errorf("tool call args.path: got %q", args.Path)
	}

	// Verify tools were declared with input_schema (not "parameters").
	if len(got.Tools) != 1 {
		t.Fatalf("expected 1 tool declared, got %d", len(got.Tools))
	}
	if got.Tools[0].Name != "read_file" || got.Tools[0].Description != "Read a file." {
		t.Errorf("tool declaration: %+v", got.Tools[0])
	}
	if got.Tools[0].InputSchema == nil || got.Tools[0].InputSchema["type"] != "object" {
		t.Errorf("tool input_schema not forwarded: %+v", got.Tools[0].InputSchema)
	}
}

// TestChat_MultiTurnWithPriorToolResult exercises the tool_result-as-a-
// user-message translation: a provider.Message carrying ToolResults (as
// agentloop.Loop emits with Role "tool" after dispatching a tool call) must
// serialize as a user-role message with tool_result content blocks —
// Anthropic has no "tool" role. Also verifies a prior assistant turn with a
// tool call round-trips into a single assistant message with a tool_use
// block matching the id used in the subsequent tool_result.
func TestChat_MultiTurnWithPriorToolResult(t *testing.T) {
	var got wireRequest
	srv := fakeAnthropicServer(t, http.StatusOK, `{
		"id": "msg_3",
		"type": "message",
		"role": "assistant",
		"model": "claude-sonnet-5",
		"content": [{"type": "text", "text": "The file says hello."}],
		"stop_reason": "end_turn",
		"usage": {"input_tokens": 30, "output_tokens": 6}
	}`, &got)
	defer srv.Close()

	p := newTestProvider(srv.URL)
	_, err := p.Chat(context.Background(), provider.ChatRequest{
		Model: "claude-sonnet-5",
		Messages: []provider.Message{
			{Role: "user", Text: "read a.txt"},
			{
				Role: "assistant",
				Text: "",
				ToolCalls: []provider.ToolCall{
					{ID: "toolu_01", Name: "read_file", ArgsJSON: `{"path":"a.txt"}`},
				},
			},
			{
				Role: "tool",
				ToolResults: []provider.ToolResult{
					{ToolCallID: "toolu_01", Name: "read_file", Content: "hello", IsError: false},
				},
			},
		},
	})
	if err != nil {
		t.Fatalf("Chat: %v", err)
	}

	if len(got.Messages) != 3 {
		t.Fatalf("expected 3 wire messages, got %d: %+v", len(got.Messages), got.Messages)
	}

	// Turn 2: assistant tool_use, no text block since Text was empty.
	asst := got.Messages[1]
	if asst.Role != "assistant" {
		t.Errorf("turn 2 role: want assistant got %q", asst.Role)
	}
	if len(asst.Content) != 1 || asst.Content[0].Type != "tool_use" {
		t.Fatalf("turn 2 content: %+v", asst.Content)
	}
	if asst.Content[0].ID != "toolu_01" || asst.Content[0].Name != "read_file" {
		t.Errorf("turn 2 tool_use block: %+v", asst.Content[0])
	}

	// Turn 3: the tool result must be a USER-role message with a
	// tool_result block (Anthropic has no "tool" role).
	toolTurn := got.Messages[2]
	if toolTurn.Role != "user" {
		t.Errorf("tool result turn role: want user (Anthropic has no tool role) got %q", toolTurn.Role)
	}
	if len(toolTurn.Content) != 1 || toolTurn.Content[0].Type != "tool_result" {
		t.Fatalf("tool result content: %+v", toolTurn.Content)
	}
	block := toolTurn.Content[0]
	if block.ToolUseID != "toolu_01" {
		t.Errorf("tool_use_id: want toolu_01 got %q", block.ToolUseID)
	}
	if block.Content != "hello" {
		t.Errorf("tool_result content: want hello got %q", block.Content)
	}
	if block.IsError {
		t.Errorf("is_error should be false")
	}
}

// TestChat_ToolResultIsError verifies IsError round-trips onto the
// tool_result block's is_error field.
func TestChat_ToolResultIsError(t *testing.T) {
	var got wireRequest
	srv := fakeAnthropicServer(t, http.StatusOK, `{
		"content": [{"type": "text", "text": "ok"}],
		"stop_reason": "end_turn",
		"usage": {"input_tokens": 1, "output_tokens": 1}
	}`, &got)
	defer srv.Close()

	p := newTestProvider(srv.URL)
	_, err := p.Chat(context.Background(), provider.ChatRequest{
		Model: "claude-sonnet-5",
		Messages: []provider.Message{
			{Role: "tool", ToolResults: []provider.ToolResult{
				{ToolCallID: "toolu_x", Name: "run_bash", Content: "boom", IsError: true},
			}},
		},
	})
	if err != nil {
		t.Fatalf("Chat: %v", err)
	}
	if len(got.Messages) != 1 || len(got.Messages[0].Content) != 1 {
		t.Fatalf("unexpected messages: %+v", got.Messages)
	}
	if !got.Messages[0].Content[0].IsError {
		t.Errorf("expected is_error true")
	}
}

// TestChat_RateLimitError429 verifies a 429 rate_limit_error response
// produces a Go error whose text retry.IsRateLimitError recognizes.
func TestChat_RateLimitError429(t *testing.T) {
	srv := fakeAnthropicServer(t, http.StatusTooManyRequests, `{
		"type": "error",
		"error": {"type": "rate_limit_error", "message": "Number of requests has exceeded your rate limit."}
	}`, nil)
	defer srv.Close()

	p := newTestProvider(srv.URL)
	_, err := p.Chat(context.Background(), provider.ChatRequest{
		Model:    "claude-sonnet-5",
		Messages: []provider.Message{{Role: "user", Text: "hi"}},
	})
	if err == nil {
		t.Fatal("expected an error for HTTP 429")
	}
	if !strings.Contains(err.Error(), "429") || !strings.Contains(err.Error(), "rate_limit_error") {
		t.Errorf("error should mention 429 and rate_limit_error, got: %v", err)
	}
	if !retry.IsRateLimitError(err) {
		t.Errorf("retry.IsRateLimitError should recognize: %v", err)
	}
}

// TestChat_OverloadedError529 verifies a 529 overloaded_error response is
// also recognized as retryable.
func TestChat_OverloadedError529(t *testing.T) {
	srv := fakeAnthropicServer(t, 529, `{
		"type": "error",
		"error": {"type": "overloaded_error", "message": "Overloaded"}
	}`, nil)
	defer srv.Close()

	p := newTestProvider(srv.URL)
	_, err := p.Chat(context.Background(), provider.ChatRequest{
		Model:    "claude-sonnet-5",
		Messages: []provider.Message{{Role: "user", Text: "hi"}},
	})
	if err == nil {
		t.Fatal("expected an error for HTTP 529")
	}
	if !retry.IsRateLimitError(err) {
		t.Errorf("retry.IsRateLimitError should recognize overloaded_error: %v", err)
	}
}

// TestChat_InvalidRequestError400 is a non-retryable error case: confirms
// the error text carries the invalid_request_error type and is NOT
// misclassified as a rate-limit error.
func TestChat_InvalidRequestError400(t *testing.T) {
	srv := fakeAnthropicServer(t, http.StatusBadRequest, `{
		"type": "error",
		"error": {"type": "invalid_request_error", "message": "max_tokens: field required"}
	}`, nil)
	defer srv.Close()

	p := newTestProvider(srv.URL)
	_, err := p.Chat(context.Background(), provider.ChatRequest{
		Model:    "claude-sonnet-5",
		Messages: []provider.Message{{Role: "user", Text: "hi"}},
	})
	if err == nil {
		t.Fatal("expected an error for HTTP 400")
	}
	if !strings.Contains(err.Error(), "invalid_request_error") {
		t.Errorf("error should mention invalid_request_error, got: %v", err)
	}
	if retry.IsRateLimitError(err) {
		t.Errorf("400 invalid_request_error should NOT be classified as a rate-limit error: %v", err)
	}
}

// TestChat_NoAPIKey_Errors confirms Chat fails fast without ever making an
// HTTP request when no API key is configured.
func TestChat_NoAPIKey_Errors(t *testing.T) {
	p := New("", "http://127.0.0.1:1", time.Second)
	_, err := p.Chat(context.Background(), provider.ChatRequest{Model: "claude-sonnet-5"})
	if err == nil || !strings.Contains(err.Error(), "no API key") {
		t.Errorf("expected 'no API key' error, got %v", err)
	}
}

// TestNew_DefaultsEndpointAndTimeout verifies New falls back to
// DefaultEndpoint/DefaultTimeout for zero-value arguments.
func TestNew_DefaultsEndpointAndTimeout(t *testing.T) {
	p := New("key", "", 0)
	if p.Endpoint != DefaultEndpoint {
		t.Errorf("Endpoint: want %q got %q", DefaultEndpoint, p.Endpoint)
	}
	if p.HTTPClient.Timeout != DefaultTimeout {
		t.Errorf("Timeout: want %v got %v", DefaultTimeout, p.HTTPClient.Timeout)
	}
}

// TestName returns the provider's identifier, used as the agent-type/budget
// key ("anthropic") once wired into a NativeRunner.
func TestName(t *testing.T) {
	p := New("key", "", 0)
	if p.Name() != "anthropic" {
		t.Errorf("Name: got %q", p.Name())
	}
}

// TestPricingFor_KnownAndUnknownModels sanity-checks the pricing table
// lookup: exact/prefix match for known models, and a non-erroring fallback
// for an unrecognized model string.
func TestPricingFor_KnownAndUnknownModels(t *testing.T) {
	in, out := pricingFor("claude-opus-4-8")
	if in != 5.00 || out != 25.00 {
		t.Errorf("opus 4.8 pricing: got %v/%v", in, out)
	}
	in, out = pricingFor("claude-haiku-4-5-20251001")
	if in != 1.00 || out != 5.00 {
		t.Errorf("haiku 4.5 dated snapshot pricing: got %v/%v", in, out)
	}
	in, out = pricingFor("some-future-unknown-model")
	if in != defaultPricing.InputPerMTok || out != defaultPricing.OutputPerMTok {
		t.Errorf("unknown model should fall back to default pricing, got %v/%v", in, out)
	}
}