// Package llm holds LLM model-identifier helpers shared by the proxy and
// the management server. The proxy normalizes model ids parsed off inbound
// requests; management normalizes the operator's registered model ids at
// synthesis time so both sides of the pricing / routing contract compare
// equal.
package llm

import (
	"regexp"
	"strings"
)

// bedrockRegionPrefixes are the cross-region inference-profile prefixes that
// front a Bedrock model id (e.g. "eu.anthropic.claude-...").
var bedrockRegionPrefixes = []string{"us.", "eu.", "apac.", "global."}

// bedrockVersionSuffix matches the trailing "-vN[:N]" or "-YYYYMMDD-vN[:N]"
// version/throughput suffix of a Bedrock model id.
var bedrockVersionSuffix = regexp.MustCompile(`-(\d{8}-)?v\d+(:\d+)?$`)

// NormalizeBedrockModel strips an ARN wrapper, a cross-region inference-profile
// prefix, and the version/throughput suffix from a Bedrock model id so it
// matches the catalog/pricing key, e.g.
// "eu.anthropic.claude-sonnet-4-5-20250929-v1:0" -> "anthropic.claude-sonnet-4-5"
// and the inference-profile ARN's last segment likewise. It is the single
// source of truth shared by the proxy's request parser (which normalizes the
// request model from the URL path), the proxy's router (which normalizes the
// operator's registered Bedrock model ids so both sides compare equal), and
// the management synthesizer (which keys per-provider pricing entries by the
// normalized id the parser will emit at billing time).
func NormalizeBedrockModel(modelID string) string {
	m := modelID
	// A full ARN (inference-profile / provisioned-throughput / foundation-model)
	// carries the model id in its last path segment.
	if strings.HasPrefix(m, "arn:") {
		if i := strings.LastIndex(m, "/"); i >= 0 {
			m = m[i+1:]
		}
	}
	for _, p := range bedrockRegionPrefixes {
		if strings.HasPrefix(m, p) {
			m = m[len(p):]
			break
		}
	}
	return bedrockVersionSuffix.ReplaceAllString(m, "")
}

// anthropicDateSuffix matches the trailing "-YYYYMMDD" release-date suffix
// Anthropic appends to a pinned model id. No other vendor in the catalog
// ends an id in eight consecutive digits, so the pattern is safe to apply
// before a lookup regardless of surface.
var anthropicDateSuffix = regexp.MustCompile(`-\d{8}$`)

// NormalizeAnthropicModel strips the trailing release-date suffix from a
// first-party Anthropic model id, e.g. "claude-sonnet-4-5-20250929" ->
// "claude-sonnet-4-5", so a dated id a client pins matches the undated one
// the operator registered. Callers try the verbatim id first and fall back
// to this, so two dated releases of the same family stay distinct wherever
// both are registered explicitly.
func NormalizeAnthropicModel(modelID string) string {
	return anthropicDateSuffix.ReplaceAllString(modelID, "")
}

// NormalizeVertexModel strips the "@version" suffix from a Vertex AI model id
// (e.g. "claude-sonnet-4-5@20250929" -> "claude-sonnet-4-5") so it matches
// the catalog/pricing key. Vertex publisher models are priced under their
// vendor surface with the bare, unversioned id.
func NormalizeVertexModel(modelID string) string {
	if at := strings.Index(modelID, "@"); at >= 0 {
		return modelID[:at]
	}
	return modelID
}