export interface ModelSpec {
	maxOutputTokens: number;
	thinkingBudget: number; // -1 = adaptive (model decides), >=0 = fixed
	isThinking: boolean;
}

export const DEFAULT_MODEL_SPECS: Record<string, ModelSpec> = {
	"gemini-pro-agent":          { maxOutputTokens: 65535, thinkingBudget: 10001, isThinking: true },
	"gemini-3-flash-agent":      { maxOutputTokens: 65536, thinkingBudget: 10000, isThinking: true },
	"gemini-3-pro-high":         { maxOutputTokens: 65535, thinkingBudget: 10001, isThinking: true },
	"gemini-3-pro-low":          { maxOutputTokens: 65535, thinkingBudget: 1001,  isThinking: true },
	"gemini-3.1-pro":            { maxOutputTokens: 65535, thinkingBudget: 10001, isThinking: true },
	"gemini-3.1-pro-high":       { maxOutputTokens: 65535, thinkingBudget: 10001, isThinking: true },
	"gemini-3.1-pro-low":        { maxOutputTokens: 65535, thinkingBudget: 1001,  isThinking: true },
	"gemini-3.1-pro-preview":    { maxOutputTokens: 65535, thinkingBudget: 10001, isThinking: true },
	"gemini-3.5-flash":          { maxOutputTokens: 65536, thinkingBudget: 10000, isThinking: true },
	"gemini-3.5-flash-medium":   { maxOutputTokens: 65536, thinkingBudget: 4000,  isThinking: true },
	"gemini-3.5-flash-low":      { maxOutputTokens: 65536, thinkingBudget: 4000,  isThinking: true },
	"gemini-3.5-flash-high":     { maxOutputTokens: 65536, thinkingBudget: 10000, isThinking: true },
	"gemini-3.6-flash-high":     { maxOutputTokens: 65536, thinkingBudget: 10000, isThinking: true },
	"gemini-3.6-flash-medium":   { maxOutputTokens: 65536, thinkingBudget: 4000,  isThinking: true },
	"gemini-3.6-flash-low":      { maxOutputTokens: 65536, thinkingBudget: 1000,  isThinking: true },
	"gemini-3.6-flash-tiered":   { maxOutputTokens: 65536, thinkingBudget: -1,    isThinking: true },
	"gemini-3-flash":            { maxOutputTokens: 65536, thinkingBudget: 4000,  isThinking: true },
	"gemini-2.5-flash":          { maxOutputTokens: 65535, thinkingBudget: 24576, isThinking: true },
	"gemini-2.5-pro":            { maxOutputTokens: 65535, thinkingBudget: 1024,  isThinking: true },
	"claude-sonnet-4-6":         { maxOutputTokens: 64000, thinkingBudget: 32768, isThinking: true },
	"claude-sonnet-4-6-thinking":{ maxOutputTokens: 64000, thinkingBudget: 32768, isThinking: true },
	"claude-opus-4-6-thinking":  { maxOutputTokens: 64000, thinkingBudget: 32768, isThinking: true },
	"gpt-oss-120b-medium":       { maxOutputTokens: 32768, thinkingBudget: 8192,  isThinking: true },
	"gpt-oss-120b":              { maxOutputTokens: 32768, thinkingBudget: 8192,  isThinking: true },
};

let modelSpecsOverride: Record<string, ModelSpec> | null = null;

/**
 * Replace the bundled model spec table with operator-provided overrides.
 * Pass `null` to restore defaults. Called once at startup from index.ts.
 */
export function setModelSpecsOverride(specs: Record<string, ModelSpec> | null): void {
	modelSpecsOverride = specs && Object.keys(specs).length > 0 ? specs : null;
}

export function getActiveModelSpecs(): Record<string, ModelSpec> {
	return modelSpecsOverride ?? DEFAULT_MODEL_SPECS;
}

const GEMINI_MAX_OUTPUT_TOKENS = 65536;
const CLAUDE_MAX_OUTPUT_TOKENS = 64000;
const FALLBACK_THINKING_BUDGET = 24576;
const CLAUDE_DEFAULT_THINKING_BUDGET = 32768;

export function getModelFamily(model: string): "claude" | "gemini" | "unknown" {
	const l = model.toLowerCase();
	if (l.includes("claude")) return "claude";
	if (l.includes("gemini")) return "gemini";
	return "unknown";
}

export function getModelSpec(model: string): ModelSpec {
	const specs = getActiveModelSpecs();
	const lower = model.toLowerCase();
	if (specs[lower]) return specs[lower];
	for (const [key, spec] of Object.entries(specs)) {
		if (lower.includes(key)) return spec;
	}
	const family = getModelFamily(model);
	if (family === "claude") return { maxOutputTokens: CLAUDE_MAX_OUTPUT_TOKENS, thinkingBudget: CLAUDE_DEFAULT_THINKING_BUDGET, isThinking: true };
	if (family === "gemini") return { maxOutputTokens: GEMINI_MAX_OUTPUT_TOKENS, thinkingBudget: FALLBACK_THINKING_BUDGET, isThinking: true };
	return { maxOutputTokens: 65536, thinkingBudget: FALLBACK_THINKING_BUDGET, isThinking: false };
}

export function isThinkingModel(model: string): boolean {
	const spec = getModelSpec(model);
	if (spec.isThinking) return true;
	const l = model.toLowerCase();
	if (l.includes("gemini")) {
		const m = l.match(/gemini-(\d+)/);
		if (m && parseInt(m[1], 10) >= 3) return true;
	}
	return false;
}