package missionclass

import (
	"sort"
	"strings"
)

// pscMission maps a PSC code prefix to mission codes. Deliberately narrow: only codes with a defensible
// mission signal are mapped, so a generic code produces no tag rather than a wrong one. Extend with
// vetted entries only; a broad code stays unmapped on purpose.
var pscMission = map[string][]string{
	"AC": {"SIGINT", "EW"}, // R&D, National Defense (curated, conservative)
}

// naicsMission maps a full NAICS code to mission codes (curated, conservative). A broad NAICS that
// carries no defensible mission signal is intentionally left empty so it produces no tag.
var naicsMission = map[string][]string{
	"541330": {}, // Engineering Services: too broad to assign a mission, intentionally empty
}

// ClassifyCodes maps a PSC code and a NAICS code to mission Hits through the curated crosswalk. The PSC
// match is by prefix, the NAICS match is exact. Mechanism is psc or naics, evidence is the matched code.
// An unmapped or broad code yields no Hit. Output is in Codes order, byte stable.
func ClassifyCodes(psc, naics string) []Hit {
	found := map[string]Hit{}
	psc = strings.ToUpper(strings.TrimSpace(psc))
	if psc != "" {
		prefixes := make([]string, 0, len(pscMission))
		for prefix := range pscMission {
			prefixes = append(prefixes, prefix)
		}
		sort.Strings(prefixes) // deterministic iteration over the prefix set
		for _, prefix := range prefixes {
			if strings.HasPrefix(psc, prefix) {
				for _, c := range pscMission[prefix] {
					found[c] = Hit{Code: c, Mechanism: MechPSC, Evidence: psc}
				}
			}
		}
	}
	naics = strings.TrimSpace(naics)
	if codes, ok := naicsMission[naics]; ok {
		for _, c := range codes {
			found[c] = Hit{Code: c, Mechanism: MechNAICS, Evidence: naics}
		}
	}
	return ordered(found)
}

// Classify unions the keyword, alias, and code mechanisms and dedupes by code, keeping the FIRST
// mechanism seen in priority order keyword, alias, code (so the most direct evidence is recorded). The
// result is in Codes order, byte stable.
func Classify(text, psc, naics string, idx AliasIndex) []Hit {
	merged := map[string]Hit{}
	for _, h := range ClassifyKeyword(text) {
		if _, ok := merged[h.Code]; !ok {
			merged[h.Code] = h
		}
	}
	for _, h := range ClassifyAlias(text, idx) {
		if _, ok := merged[h.Code]; !ok {
			merged[h.Code] = h
		}
	}
	for _, h := range ClassifyCodes(psc, naics) {
		if _, ok := merged[h.Code]; !ok {
			merged[h.Code] = h
		}
	}
	return ordered(merged)
}