package apicompat

import (
	"encoding/json"
	"testing"

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

// These tests drive the exact production path for Chat Completions clients on an
// Anthropic-platform group: ForwardAsChatCompletions runs
// ChatCompletionsToResponses → ResponsesToAnthropicRequest
// (gateway_forward_as_chat_completions.go), then forwards the Anthropic body
// upstream. They assert the tool-pairing repair holds through that full chain,
// not only for codex-style Responses input.
func ccChainToAnthropic(t *testing.T, ccReq *ChatCompletionsRequest) []AnthropicMessage {
	t.Helper()
	respReq, err := ChatCompletionsToResponses(ccReq)
	require.NoError(t, err)
	anthReq, err := ResponsesToAnthropicRequest(respReq)
	require.NoError(t, err)
	assertAnthropicPairing(t, anthReq.Messages)
	return anthReq.Messages
}

// Reproduces the production 400:
//
//	unexpected ...content.0: tool_use_id found in tool_result blocks:
//	call_00_TgfbRvKlnD7oK6Dg00sL1661. Each tool_result block must have a
//	corresponding tool_use block in the previous message.
//
// A Chat Completions client trimmed its history and kept a tool result whose
// announcing assistant tool_calls message was dropped (sliding-window context
// management). The orphan tool_result has no matching tool_use → upstream 400.
// The repair drops the orphan so the request is valid.
func TestCCChain_OrphanToolResultFromTrimmedHistory(t *testing.T) {
	orphanID := "call_00_TgfbRvKlnD7oK6Dg00sL1661"
	msgs := ccChainToAnthropic(t, &ChatCompletionsRequest{
		Model: "deepseek-v4-pro",
		Messages: []ChatMessage{
			{Role: "user", Content: json.RawMessage(`"search the web for X"`)},
			// The assistant tool_calls message that announced orphanID was trimmed.
			{Role: "tool", ToolCallID: orphanID, Content: json.RawMessage(`"stale search results"`)},
			{Role: "assistant", Content: json.RawMessage(`"Here is what I found."`)},
			{Role: "user", Content: json.RawMessage(`"thanks, now do Y"`)},
		},
	})
	for _, m := range msgs {
		require.Falsef(t, hasToolResult(parseContentBlocks(m.Content), orphanID),
			"orphan tool_result %s should have been dropped", orphanID)
	}
}

// A parallel web_search where one sibling's result never came back (the tool
// failed/was skipped). The unanswered tool_use would otherwise trip Anthropic's
// "tool_use without tool_result" check; the repair drops it.
func TestCCChain_ParallelToolOneResultMissing(t *testing.T) {
	msgs := ccChainToAnthropic(t, &ChatCompletionsRequest{
		Model: "deepseek-v4-pro",
		Messages: []ChatMessage{
			{Role: "user", Content: json.RawMessage(`"search A and B"`)},
			{Role: "assistant", Content: json.RawMessage(`"searching both"`), ToolCalls: []ChatToolCall{
				{ID: "call_a", Type: "function", Function: ChatFunctionCall{Name: "web_search", Arguments: `{"q":"A"}`}},
				{ID: "call_b", Type: "function", Function: ChatFunctionCall{Name: "web_search", Arguments: `{"q":"B"}`}},
			}},
			{Role: "tool", ToolCallID: "call_a", Content: json.RawMessage(`"result A"`)},
			// call_b's result is missing.
		},
	})
	for _, m := range msgs {
		require.Falsef(t, hasToolUse(parseContentBlocks(m.Content), "call_b"),
			"unanswered tool_use call_b should have been dropped")
	}
}

// Baseline: a well-formed multi-round tool history (text + tool_calls per
// assistant turn) converts and pairs correctly through the full chain.
func TestCCChain_WellFormedMultiRound(t *testing.T) {
	msgs := ccChainToAnthropic(t, &ChatCompletionsRequest{
		Model: "deepseek-v4-pro",
		Messages: []ChatMessage{
			{Role: "user", Content: json.RawMessage(`"do A then B"`)},
			{Role: "assistant", Content: json.RawMessage(`"running A"`), ToolCalls: []ChatToolCall{
				{ID: "call_a", Type: "function", Function: ChatFunctionCall{Name: "exec", Arguments: `{"cmd":"A"}`}},
			}},
			{Role: "tool", ToolCallID: "call_a", Content: json.RawMessage(`"A ok"`)},
			{Role: "assistant", Content: json.RawMessage(`"A done, running B"`), ToolCalls: []ChatToolCall{
				{ID: "call_b", Type: "function", Function: ChatFunctionCall{Name: "exec", Arguments: `{"cmd":"B"}`}},
			}},
			{Role: "tool", ToolCallID: "call_b", Content: json.RawMessage(`"B ok"`)},
			{Role: "assistant", Content: json.RawMessage(`"all done"`)},
		},
	})
	// Both calls survive and stay paired (assertAnthropicPairing already checks).
	var sawA, sawB bool
	for _, m := range msgs {
		blocks := parseContentBlocks(m.Content)
		sawA = sawA || hasToolUse(blocks, "call_a")
		sawB = sawB || hasToolUse(blocks, "call_b")
	}
	require.True(t, sawA && sawB, "both well-formed calls should be preserved")
}