// Package provider defines a provider-neutral chat/tool-use interface. It is
// independent of any one wire format (OpenAI-compatible, Anthropic Messages,
// Gemini, etc.) so that internal/agentloop's tool-use control flow can drive
// any backend that implements Provider.
//
// Phase 1 ships exactly one implementation, internal/provider/openaicompat,
// which adapts the existing internal/llm.Client. Later phases add native
// Anthropic/OpenAI/Google/Groq/OpenRouter adapters without touching agentloop.
package provider

import "context"

// Message is one turn in a chat conversation, in provider-neutral shape.
type Message struct {
	Role        string // "system" | "user" | "assistant" | "tool"
	Text        string
	ToolCalls   []ToolCall   // set on assistant turns that invoke tools
	ToolResults []ToolResult // set on tool-result turns
}

// ToolCall is a single tool invocation requested by the model.
type ToolCall struct {
	ID       string
	Name     string
	ArgsJSON string
}

// ToolResult is the outcome of executing a ToolCall, fed back to the model.
type ToolResult struct {
	ToolCallID string
	Name       string
	Content    string
	IsError    bool
}

// ToolSpec declares a tool the model may call.
type ToolSpec struct {
	Name                 string
	Description          string
	ParametersJSONSchema map[string]any
}

// ChatRequest captures the parameters of a single chat completion call.
type ChatRequest struct {
	Model       string
	System      string
	Messages    []Message
	Tools       []ToolSpec
	Temperature *float64
	MaxTokens   int
}

// Usage reports token accounting and (when known) cost for a single call.
type Usage struct {
	InputTokens  int
	OutputTokens int
	CostUSD      float64
}

// ChatResponse is the aggregated result of a chat completion.
type ChatResponse struct {
	Text       string
	ToolCalls  []ToolCall
	StopReason string
	Usage      Usage
}

// Provider is a chat/tool-use backend: one per LLM vendor/wire-format.
type Provider interface {
	Name() string
	Chat(ctx context.Context, req ChatRequest) (*ChatResponse, error)
}