// Package mcp provides the MCP (Model Context Protocol) server for claude-mnemonic.
package mcp

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

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
	"github.com/stretchr/testify/suite"
)

// ServerSuite is a test suite for MCP Server operations.
type ServerSuite struct {
	suite.Suite
}

func TestServerSuite(t *testing.T) {
	suite.Run(t, new(ServerSuite))
}

// TestNewServer tests server creation.
func (s *ServerSuite) TestNewServer() {
	server := NewServer(nil, "1.0.0")
	s.NotNil(server)
	s.Nil(server.searchMgr)
	s.Equal("1.0.0", server.version)
}

// TestRequest tests Request struct JSON marshaling.
func TestRequest(t *testing.T) {
	tests := []struct {
		name     string
		req      Request
		expected string
	}{
		{
			name: "initialize request",
			req: Request{
				JSONRPC: "2.0",
				ID:      1,
				Method:  "initialize",
			},
			expected: `{"jsonrpc":"2.0","id":1,"method":"initialize"}`,
		},
		{
			name: "tools/list request",
			req: Request{
				JSONRPC: "2.0",
				ID:      "abc",
				Method:  "tools/list",
			},
			expected: `{"jsonrpc":"2.0","id":"abc","method":"tools/list"}`,
		},
		{
			name: "tools/call with params",
			req: Request{
				JSONRPC: "2.0",
				ID:      2,
				Method:  "tools/call",
				Params:  json.RawMessage(`{"name":"search","arguments":{}}`),
			},
			expected: `{"jsonrpc":"2.0","id":2,"method":"tools/call","params":{"name":"search","arguments":{}}}`,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			data, err := json.Marshal(tt.req)
			require.NoError(t, err)
			assert.JSONEq(t, tt.expected, string(data))

			// Test unmarshaling
			var parsed Request
			err = json.Unmarshal(data, &parsed)
			require.NoError(t, err)
			assert.Equal(t, tt.req.JSONRPC, parsed.JSONRPC)
			assert.Equal(t, tt.req.Method, parsed.Method)
		})
	}
}

// TestResponse tests Response struct JSON marshaling.
func TestResponse(t *testing.T) {
	tests := []struct {
		name     string
		resp     Response
		expected string
	}{
		{
			name: "success response",
			resp: Response{
				JSONRPC: "2.0",
				ID:      1,
				Result:  map[string]string{"status": "ok"},
			},
			expected: `{"jsonrpc":"2.0","id":1,"result":{"status":"ok"}}`,
		},
		{
			name: "error response",
			resp: Response{
				JSONRPC: "2.0",
				ID:      2,
				Error: &Error{
					Code:    -32600,
					Message: "Invalid Request",
				},
			},
			expected: `{"jsonrpc":"2.0","id":2,"error":{"code":-32600,"message":"Invalid Request"}}`,
		},
		{
			name: "error with data",
			resp: Response{
				JSONRPC: "2.0",
				ID:      3,
				Error: &Error{
					Code:    -32602,
					Message: "Invalid params",
					Data:    "missing field",
				},
			},
			expected: `{"jsonrpc":"2.0","id":3,"error":{"code":-32602,"message":"Invalid params","data":"missing field"}}`,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			data, err := json.Marshal(tt.resp)
			require.NoError(t, err)
			assert.JSONEq(t, tt.expected, string(data))
		})
	}
}

// TestError tests Error struct.
func TestError(t *testing.T) {
	tests := []struct {
		name     string
		err      Error
		expected string
	}{
		{
			name: "parse error",
			err: Error{
				Code:    -32700,
				Message: "Parse error",
			},
			expected: `{"code":-32700,"message":"Parse error"}`,
		},
		{
			name: "method not found",
			err: Error{
				Code:    -32601,
				Message: "Method not found",
			},
			expected: `{"code":-32601,"message":"Method not found"}`,
		},
		{
			name: "invalid params",
			err: Error{
				Code:    -32602,
				Message: "Invalid params",
				Data:    "details here",
			},
			expected: `{"code":-32602,"message":"Invalid params","data":"details here"}`,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			data, err := json.Marshal(tt.err)
			require.NoError(t, err)
			assert.JSONEq(t, tt.expected, string(data))
		})
	}
}

// TestToolCallParams tests ToolCallParams struct.
func TestToolCallParams(t *testing.T) {
	tests := []struct {
		name     string
		input    string
		expected ToolCallParams
	}{
		{
			name:  "search tool call",
			input: `{"name":"search","arguments":{"query":"test"}}`,
			expected: ToolCallParams{
				Name:      "search",
				Arguments: json.RawMessage(`{"query":"test"}`),
			},
		},
		{
			name:  "decisions tool call",
			input: `{"name":"decisions","arguments":{"query":"auth"}}`,
			expected: ToolCallParams{
				Name:      "decisions",
				Arguments: json.RawMessage(`{"query":"auth"}`),
			},
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			var params ToolCallParams
			err := json.Unmarshal([]byte(tt.input), &params)
			require.NoError(t, err)
			assert.Equal(t, tt.expected.Name, params.Name)
		})
	}
}

// TestTool tests Tool struct.
func TestTool(t *testing.T) {
	tool := Tool{
		Name:        "search",
		Description: "Search observations",
		InputSchema: map[string]any{
			"type": "object",
			"properties": map[string]any{
				"query": map[string]any{"type": "string"},
			},
		},
	}

	data, err := json.Marshal(tool)
	require.NoError(t, err)

	var parsed Tool
	err = json.Unmarshal(data, &parsed)
	require.NoError(t, err)
	assert.Equal(t, "search", parsed.Name)
	assert.Equal(t, "Search observations", parsed.Description)
}

// TestTimelineParams tests TimelineParams struct.
func TestTimelineParams(t *testing.T) {
	tests := []struct {
		name     string
		input    string
		expected TimelineParams
	}{
		{
			name:  "with anchor_id",
			input: `{"anchor_id":123,"before":5,"after":5}`,
			expected: TimelineParams{
				AnchorID: 123,
				Before:   5,
				After:    5,
			},
		},
		{
			name:  "with query",
			input: `{"query":"test query","project":"my-project"}`,
			expected: TimelineParams{
				Query:   "test query",
				Project: "my-project",
			},
		},
		{
			name:  "full params",
			input: `{"anchor_id":100,"query":"search","before":10,"after":20,"project":"proj","obs_type":"bugfix","concepts":"security","files":"main.go","dateStart":1234567890,"dateEnd":9876543210,"format":"full"}`,
			expected: TimelineParams{
				AnchorID:  100,
				Query:     "search",
				Before:    10,
				After:     20,
				Project:   "proj",
				ObsType:   "bugfix",
				Concepts:  "security",
				Files:     "main.go",
				DateStart: 1234567890,
				DateEnd:   9876543210,
				Format:    "full",
			},
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			var params TimelineParams
			err := json.Unmarshal([]byte(tt.input), &params)
			require.NoError(t, err)
			assert.Equal(t, tt.expected.AnchorID, params.AnchorID)
			assert.Equal(t, tt.expected.Query, params.Query)
			assert.Equal(t, tt.expected.Project, params.Project)
		})
	}
}

// TestHandleInitialize tests the initialize handler.
func TestHandleInitialize(t *testing.T) {
	server := NewServer(nil, "1.2.3")

	req := &Request{
		JSONRPC: "2.0",
		ID:      1,
		Method:  "initialize",
	}

	resp := server.handleInitialize(req)

	assert.Equal(t, "2.0", resp.JSONRPC)
	assert.Equal(t, 1, resp.ID)
	assert.Nil(t, resp.Error)
	assert.NotNil(t, resp.Result)

	result, ok := resp.Result.(map[string]any)
	require.True(t, ok)
	assert.Equal(t, "2024-11-05", result["protocolVersion"])

	serverInfo, ok := result["serverInfo"].(map[string]any)
	require.True(t, ok)
	assert.Equal(t, "claude-mnemonic", serverInfo["name"])
	assert.Equal(t, "1.2.3", serverInfo["version"])
}

// TestHandleToolsList tests the tools/list handler.
func TestHandleToolsList(t *testing.T) {
	server := NewServer(nil, "1.0.0")

	req := &Request{
		JSONRPC: "2.0",
		ID:      1,
		Method:  "tools/list",
	}

	resp := server.handleToolsList(req)

	assert.Equal(t, "2.0", resp.JSONRPC)
	assert.Equal(t, 1, resp.ID)
	assert.Nil(t, resp.Error)

	result, ok := resp.Result.(map[string]any)
	require.True(t, ok)

	tools, ok := result["tools"].([]Tool)
	require.True(t, ok)
	assert.NotEmpty(t, tools)

	// Verify expected tools are present
	toolNames := make(map[string]bool)
	for _, tool := range tools {
		toolNames[tool.Name] = true
	}

	expectedTools := []string{
		"search", "timeline", "decisions", "changes",
		"how_it_works", "find_by_concept", "find_by_file",
		"find_by_type", "get_recent_context", "get_context_timeline",
		"get_timeline_by_query",
	}

	for _, name := range expectedTools {
		assert.True(t, toolNames[name], "expected tool %s to be present", name)
	}
}

// TestHandleRequest tests request routing.
func TestHandleRequest(t *testing.T) {
	server := NewServer(nil, "1.0.0")
	ctx := context.Background()

	tests := []struct {
		name         string
		req          *Request
		expectError  bool
		errorCode    int
		errorMessage string
	}{
		{
			name: "initialize method",
			req: &Request{
				JSONRPC: "2.0",
				ID:      1,
				Method:  "initialize",
			},
			expectError: false,
		},
		{
			name: "tools/list method",
			req: &Request{
				JSONRPC: "2.0",
				ID:      2,
				Method:  "tools/list",
			},
			expectError: false,
		},
		{
			name: "unknown method",
			req: &Request{
				JSONRPC: "2.0",
				ID:      3,
				Method:  "unknown_method",
			},
			expectError:  true,
			errorCode:    -32601,
			errorMessage: "Method not found",
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			resp := server.handleRequest(ctx, tt.req)

			assert.Equal(t, "2.0", resp.JSONRPC)
			assert.Equal(t, tt.req.ID, resp.ID)

			if tt.expectError {
				require.NotNil(t, resp.Error)
				assert.Equal(t, tt.errorCode, resp.Error.Code)
				assert.Equal(t, tt.errorMessage, resp.Error.Message)
			} else {
				assert.Nil(t, resp.Error)
				assert.NotNil(t, resp.Result)
			}
		})
	}
}

// TestHandleToolsCall_InvalidParams tests tools/call with invalid params.
func TestHandleToolsCall_InvalidParams(t *testing.T) {
	server := NewServer(nil, "1.0.0")
	ctx := context.Background()

	req := &Request{
		JSONRPC: "2.0",
		ID:      1,
		Method:  "tools/call",
		Params:  json.RawMessage(`invalid json`),
	}

	resp := server.handleToolsCall(ctx, req)

	require.NotNil(t, resp.Error)
	assert.Equal(t, -32602, resp.Error.Code)
	assert.Equal(t, "Invalid params", resp.Error.Message)
}

// TestCallTool_UnknownTool tests callTool with unknown tool name.
func TestCallTool_UnknownTool(t *testing.T) {
	server := NewServer(nil, "1.0.0")
	ctx := context.Background()

	_, err := server.callTool(ctx, "nonexistent_tool", json.RawMessage(`{}`))
	require.Error(t, err)
	assert.Contains(t, err.Error(), "unknown tool")
}

// TestCallTool_InvalidArgs tests callTool with invalid arguments.
func TestCallTool_InvalidArgs(t *testing.T) {
	server := NewServer(nil, "1.0.0")
	ctx := context.Background()

	_, err := server.callTool(ctx, "search", json.RawMessage(`invalid json`))
	require.Error(t, err)
	assert.Contains(t, err.Error(), "invalid arguments")
}

// TestSendResponse tests response sending.
func TestSendResponse(t *testing.T) {
	var buf bytes.Buffer
	server := &Server{
		stdout: &buf,
	}

	resp := &Response{
		JSONRPC: "2.0",
		ID:      1,
		Result:  map[string]string{"status": "ok"},
	}

	server.sendResponse(resp)

	output := buf.String()
	assert.Contains(t, output, `"jsonrpc":"2.0"`)
	assert.Contains(t, output, `"id":1`)
	assert.Contains(t, output, `"result"`)
}

// TestSendError tests error response sending.
func TestSendError(t *testing.T) {
	var buf bytes.Buffer
	server := &Server{
		stdout: &buf,
	}

	server.sendError(1, -32700, "Parse error", "details")

	output := buf.String()
	assert.Contains(t, output, `"error"`)
	assert.Contains(t, output, `-32700`)
	assert.Contains(t, output, `"Parse error"`)
}

// TestRun_ParseError tests Run with invalid JSON input.
func TestRun_ParseError(t *testing.T) {
	var stdout bytes.Buffer
	stdin := strings.NewReader("invalid json\n")

	server := &Server{
		stdin:  stdin,
		stdout: &stdout,
	}

	err := server.Run(context.Background())
	require.NoError(t, err)

	output := stdout.String()
	assert.Contains(t, output, `"error"`)
	assert.Contains(t, output, `-32700`)
	assert.Contains(t, output, `"Parse error"`)
}

// TestRun_EmptyLine tests Run skips empty lines.
func TestRun_EmptyLine(t *testing.T) {
	var stdout bytes.Buffer
	stdin := strings.NewReader("\n\n")

	server := &Server{
		stdin:  stdin,
		stdout: &stdout,
	}

	err := server.Run(context.Background())
	require.NoError(t, err)

	// Should be empty - no responses for empty lines
	assert.Empty(t, stdout.String())
}

// TestRun_ValidRequest tests Run with a valid request.
func TestRun_ValidRequest(t *testing.T) {
	var stdout bytes.Buffer
	req := `{"jsonrpc":"2.0","id":1,"method":"initialize"}`
	stdin := strings.NewReader(req + "\n")

	server := &Server{
		stdin:   stdin,
		stdout:  &stdout,
		version: "1.0.0",
	}

	err := server.Run(context.Background())
	require.NoError(t, err)

	output := stdout.String()
	assert.Contains(t, output, `"jsonrpc":"2.0"`)
	assert.Contains(t, output, `"result"`)
	assert.Contains(t, output, `"protocolVersion"`)
}

// TestJSONRPCErrorCodes tests standard JSON-RPC error codes.
func TestJSONRPCErrorCodes(t *testing.T) {
	errorCodes := map[string]int{
		"Parse error":      -32700,
		"Invalid Request":  -32600,
		"Method not found": -32601,
		"Invalid params":   -32602,
		"Internal error":   -32603,
	}

	for msg, code := range errorCodes {
		t.Run(msg, func(t *testing.T) {
			err := Error{Code: code, Message: msg}
			assert.Equal(t, code, err.Code)
			assert.Equal(t, msg, err.Message)
		})
	}
}

// TestToolListContainsExpectedSchemas tests that tool schemas are valid.
func TestToolListContainsExpectedSchemas(t *testing.T) {
	server := NewServer(nil, "1.0.0")

	req := &Request{
		JSONRPC: "2.0",
		ID:      1,
		Method:  "tools/list",
	}

	resp := server.handleToolsList(req)
	result := resp.Result.(map[string]any)
	tools := result["tools"].([]Tool)

	for _, tool := range tools {
		assert.NotEmpty(t, tool.Name)
		assert.NotEmpty(t, tool.Description)
		assert.NotNil(t, tool.InputSchema)

		// Check schema has type
		schema := tool.InputSchema
		_, hasType := schema["type"]
		assert.True(t, hasType, "tool %s schema should have type", tool.Name)
	}
}