package config

import (
	"fmt"
	"sort"
	"strings"
)

// Preset describes a known OpenAI-compatible provider. All presets use
// "Authorization: Bearer <api_key>" against <base_url>/chat/completions.
type Preset struct {
	Name         string
	BaseURL      string
	DefaultModel string
	// KeyEnv is an additional env var read for the API key if none is configured.
	KeyEnv string
	Source string
}

// Presets: values verified against provider docs (see Source) on 2026-10-25.
var Presets = map[string]Preset{
	"openai":     {Name: "openai", BaseURL: "https://api.openai.com/v1", DefaultModel: "gpt-4o-mini", KeyEnv: "OPENAI_API_KEY", Source: "https://platform.openai.com/docs/api-reference"},
	"openrouter": {Name: "openrouter", BaseURL: "https://openrouter.ai/api/v1", DefaultModel: "openai/gpt-4o-mini", KeyEnv: "OPENROUTER_API_KEY", Source: "https://openrouter.ai/docs"},
	"ollama":     {Name: "ollama", BaseURL: "http://localhost:11434/v1", DefaultModel: "llama3.1", Source: "https://github.com/ollama/ollama/blob/main/docs/openai.md"},
	// Dahl: OpenAI-compatible inference on the Gonka network.
	"dahl": {Name: "dahl", BaseURL: "https://inference.dahl.global/v1", DefaultModel: "MiniMaxAI/MiniMax-M2.7", KeyEnv: "DAHL_API_KEY", Source: "https://docs.dahl.global/"},
	// GonkaRouter: OpenAI-/Anthropic-compatible router on the Gonka network.
	"gonkarouter": {Name: "gonkarouter", BaseURL: "https://api.gonkarouter.io/v1", DefaultModel: "MiniMaxAI/MiniMax-M2.7", KeyEnv: "GONKAROUTER_API_KEY", Source: "https://gonkarouter.io/docs"},
}

// PresetNames returns known provider names plus "custom".
func PresetNames() []string {
	out := []string{"custom"}
	for k := range Presets {
		out = append(out, k)
	}
	sort.Strings(out)
	return out
}

// applyPreset fills empty base_url/model/api_key from the selected provider preset.
// Explicit config values always win. "custom" requires base_url and model.
func applyPreset(l *LLM, get func(string) string) error {
	name := strings.ToLower(strings.TrimSpace(l.Provider))
	if name == "" {
		name = "openai"
	}
	l.Provider = name
	if name == "custom" {
		return nil
	}
	p, ok := Presets[name]
	if !ok {
		return fmt.Errorf("unknown llm.provider %q (known: %s)", name, strings.Join(PresetNames(), ", "))
	}
	if l.BaseURL == "" {
		l.BaseURL = p.BaseURL
	}
	if l.Model == "" {
		l.Model = p.DefaultModel
	}
	if l.APIKey == "" && p.KeyEnv != "" {
		l.APIKey = get(p.KeyEnv)
	}
	return nil
}