package dxcc

import "strings"

// The dxccByName table itself lives in dxcc_names_gen.go (generated by joining
// cty.dat to the authoritative ARRL/ADIF entity list). cty.dat doesn't carry
// the ADIF DXCC number, so we map its entity names → numbers here to stamp
// MY_DXCC / DXCC at log time without a network round-trip.

// EntityDXCC returns the ADIF DXCC entity number for the given cty.dat entity
// name, or 0 when unknown (callers should then leave the field empty rather
// than guess). Case-insensitive and whitespace-tolerant.
func EntityDXCC(name string) int {
	if name == "" {
		return 0
	}
	// Fast path: exact (lower-cased) match against the cty.dat names.
	if n := dxccByName[strings.ToLower(strings.TrimSpace(name))]; n != 0 {
		return n
	}
	// Fallback: canonicalise so abbreviation/spelling differences still match
	// (e.g. an ADIF import that wrote "Lord Howe I." instead of cty.dat's
	// "Lord Howe Island").
	if n := dxccByCanon[canonEntity(name)]; n != 0 {
		return n
	}
	// Last resort: cty.dat pseudo-entities (Sicily, African Italy) report a
	// parent DXCC entity for the number.
	if c := CanonicalEntityName(name); !strings.EqualFold(c, name) {
		return dxccByName[strings.ToLower(strings.TrimSpace(c))]
	}
	return 0
}

// dxccByCanon is dxccByName re-keyed by the canonical entity form, built once.
var dxccByCanon = func() map[string]int {
	m := make(map[string]int, len(dxccByName))
	for name, num := range dxccByName {
		m[canonEntity(name)] = num
	}
	return m
}()

// canonEntity reduces an entity name to a canonical token stream, expanding the
// common abbreviations that differ between naming conventions and normalising
// punctuation / "&".
func canonEntity(s string) string {
	s = strings.ToLower(strings.TrimSpace(s))
	s = strings.ReplaceAll(s, "&", " and ")
	fields := strings.FieldsFunc(s, func(r rune) bool {
		switch r {
		case ' ', '.', ',', '-', '\'', '(', ')', '/':
			return true
		}
		return false
	})
	for i, w := range fields {
		switch w {
		case "i":
			fields[i] = "island"
		case "is":
			fields[i] = "islands"
		case "st":
			fields[i] = "saint"
		case "mt":
			fields[i] = "mount"
		case "rep":
			fields[i] = "republic"
		case "dem":
			fields[i] = "democratic"
		case "fed":
			fields[i] = "federal"
		}
	}
	return strings.Join(fields, " ")
}

// ctyEntityAliases maps cty.dat's non-DXCC pseudo-entities — the CQ-zone /
// WAE splits AD1C lists separately — onto the ARRL DXCC entity they belong
// to. cty.dat reports e.g. "Sicily" so contesters get the right zones, but
// for DXCC (and the COUNTRY field) they are Italy.
var ctyEntityAliases = map[string]string{
	"sicily":        "Italy",
	"african italy": "Italy",
	// NB: Sardinia is intentionally absent — it's a real DXCC entity.
}

// CanonicalEntityName normalises a cty.dat entity name to its ARRL DXCC
// entity. Names that already are DXCC entities pass through unchanged.
func CanonicalEntityName(name string) string {
	if c, ok := ctyEntityAliases[strings.ToLower(strings.TrimSpace(name))]; ok {
		return c
	}
	return name
}