package gogpt

import (
	"context"
	"errors"
	"net/http"
)

var (
	ErrCompletionUnsupportedModel = errors.New("this model is not supported with this method, please use CreateChatCompletion client method instead") //nolint:lll
)

// GPT3 Defines the models provided by OpenAI to use when generating
// completions from OpenAI.
// GPT3 Models are designed for text-based tasks. For code-specific
// tasks, please refer to the Codex series of models.
const (
	GPT432K0314             = "gpt-4-32k-0314"
	GPT432K                 = "gpt-4-32k"
	GPT40314                = "gpt-4-0314"
	GPT4                    = "gpt-4"
	GPT3Dot5Turbo0301       = "gpt-3.5-turbo-0301"
	GPT3Dot5Turbo           = "gpt-3.5-turbo"
	GPT3TextDavinci003      = "text-davinci-003"
	GPT3TextDavinci002      = "text-davinci-002"
	GPT3TextCurie001        = "text-curie-001"
	GPT3TextBabbage001      = "text-babbage-001"
	GPT3TextAda001          = "text-ada-001"
	GPT3TextDavinci001      = "text-davinci-001"
	GPT3DavinciInstructBeta = "davinci-instruct-beta"
	GPT3Davinci             = "davinci"
	GPT3CurieInstructBeta   = "curie-instruct-beta"
	GPT3Curie               = "curie"
	GPT3Ada                 = "ada"
	GPT3Babbage             = "babbage"
)

// Codex Defines the models provided by OpenAI.
// These models are designed for code-specific tasks, and use
// a different tokenizer which optimizes for whitespace.
const (
	CodexCodeDavinci002 = "code-davinci-002"
	CodexCodeCushman001 = "code-cushman-001"
	CodexCodeDavinci001 = "code-davinci-001"
)

// CompletionRequest represents a request structure for completion API.
type CompletionRequest struct {
	Model            string         `json:"model"`
	Prompt           string         `json:"prompt,omitempty"`
	Suffix           string         `json:"suffix,omitempty"`
	MaxTokens        int            `json:"max_tokens,omitempty"`
	Temperature      float32        `json:"temperature,omitempty"`
	TopP             float32        `json:"top_p,omitempty"`
	N                int            `json:"n,omitempty"`
	Stream           bool           `json:"stream,omitempty"`
	LogProbs         int            `json:"logprobs,omitempty"`
	Echo             bool           `json:"echo,omitempty"`
	Stop             []string       `json:"stop,omitempty"`
	PresencePenalty  float32        `json:"presence_penalty,omitempty"`
	FrequencyPenalty float32        `json:"frequency_penalty,omitempty"`
	BestOf           int            `json:"best_of,omitempty"`
	LogitBias        map[string]int `json:"logit_bias,omitempty"`
	User             string         `json:"user,omitempty"`
}

// CompletionChoice represents one of possible completions.
type CompletionChoice struct {
	Text         string        `json:"text"`
	Index        int           `json:"index"`
	FinishReason string        `json:"finish_reason"`
	LogProbs     LogprobResult `json:"logprobs"`
}

// LogprobResult represents logprob result of Choice.
type LogprobResult struct {
	Tokens        []string             `json:"tokens"`
	TokenLogprobs []float32            `json:"token_logprobs"`
	TopLogprobs   []map[string]float32 `json:"top_logprobs"`
	TextOffset    []int                `json:"text_offset"`
}

// CompletionResponse represents a response structure for completion API.
type CompletionResponse struct {
	ID      string             `json:"id"`
	Object  string             `json:"object"`
	Created int64              `json:"created"`
	Model   string             `json:"model"`
	Choices []CompletionChoice `json:"choices"`
	Usage   Usage              `json:"usage"`
}

// CreateCompletion — API call to create a completion. This is the main endpoint of the API. Returns new text as well
// as, if requested, the probabilities over each alternative token at each position.
//
// If using a fine-tuned model, simply provide the model's ID in the CompletionRequest object,
// and the server will use the model's parameters to generate the completion.
func (c *Client) CreateCompletion(
	ctx context.Context,
	request CompletionRequest,
) (response CompletionResponse, err error) {
	if request.Model == GPT3Dot5Turbo0301 || request.Model == GPT3Dot5Turbo {
		err = ErrCompletionUnsupportedModel
		return
	}

	urlSuffix := "/completions"
	req, err := c.requestBuilder.build(ctx, http.MethodPost, c.fullURL(urlSuffix), request)
	if err != nil {
		return
	}

	err = c.sendRequest(req, &response)
	return
}