package game

import (
	"fmt"
	"log"
	"strings"

	"thehouseoficarus/internal/color"
	"thehouseoficarus/internal/net"
	"thehouseoficarus/internal/player"
)

func (g *Game) handleAccountName(sess *net.Session, input string) {
	name := strings.TrimSpace(input)
	if name == "" {
		sess.Write("Account name: ")
		return
	}
	actualName, err := g.AccountStore.FindAccount(name)
	if err == nil {
		sess.Account = &player.Account{Name: actualName}
		sess.SetAuthName(actualName)
		sess.SetState(net.StatePassword)
		sess.SetEcho(false)
		sess.Write("Password: ")
	} else {
		if verr := player.ValidName(name); verr != nil {
			sess.WriteLine(verr.Error())
			sess.Write("Account name: ")
			return
		}
		sess.Account = &player.Account{Name: name}
		sess.SetAuthName(name)
		sess.SetState(net.StateNewAccountPass)
		sess.SetEcho(false)
		sess.WriteLine("\r\nOh, a new visitor to this rock!")
		sess.Write("Choose password: ")
	}
}

func (g *Game) handlePassword(sess *net.Session, input string) {
	if input == "" {
		sess.Write("Password: ")
		return
	}
	if len(input) > 128 {
		sess.SetEcho(true)
		sess.WriteLine("Wrong password.")
		sess.SetState(net.StateAccountName)
		sess.Write("Account name: ")
		return
	}
	acc, err := g.AccountStore.LoadAccount(sess.Account.Name)
	if err != nil {
		sess.SetEcho(true)
		sess.WriteLine("Error loading account.")
		sess.SetState(net.StateAccountName)
		sess.Write("Account name: ")
		return
	}
	if !player.CheckPassword(input, acc.PasswordHash) {
		sess.SetEcho(true)
		sess.WriteLine("Wrong password.")
		sess.SetState(net.StateAccountName)
		sess.Write("Account name: ")
		return
	}
	auth := passwordAuth{ok: true, stored: acc.PasswordHash}
	// Transparent upgrade: legacy single-pass SHA-256 hashes rehash to
	// Argon2id after a successful verification. A failed save keeps the
	// legacy hash and retries on the next login.
	if player.NeedsRehash(acc.PasswordHash) {
		if hash, hashErr := player.HashPassword(input); hashErr == nil {
			auth.rehash = hash
		} else {
			log.Printf("login: password rehash for %s: %v", acc.Name, hashErr)
		}
	}
	g.applyPasswordAuth(sess, auth)
}

// passwordAuth carries the result of the EXPENSIVE password work (Argon2id
// verification and any rehash), which runs on the caller's connection
// goroutine — never on the owner, where a burst of logins would stall
// every command and tick behind password hashing.
type passwordAuth struct {
	ok bool
	// loadErr marks an account read failure off the owner: the owner task
	// renders it distinctly from a wrong password.
	loadErr bool
	// stored is the hash that was verified; the owner task re-checks the
	// file against it so a password change, rename, or delete made during
	// verification cannot authorize a stale login.
	stored string
	// rehash is an upgraded hash to persist after a successful check.
	rehash string
}

// handlePasswordOffOwner verifies the password on the caller's connection
// goroutine and submits one owner task for the (cheap) state transition.
// The production entry point; handlePassword stays for direct HandleSession
// callers (tests) but hashes on the owner there.
func (g *Game) handlePasswordOffOwner(sess *net.Session, input string) {
	if input == "" || len(input) > 128 {
		// These checks touch no session state, so they are race-free off
		// the owner; they also keep Argon2id off absurd inputs.
		tooshort := input == ""
		g.RunOnOwner(func() {
			if g.isShuttingDown() {
				return
			}
			if tooshort {
				// Echo stays disabled: the next attempt is also a password.
				sess.Write("Password: ")
				return
			}
			sess.SetEcho(true)
			sess.WriteLine("Wrong password.")
			sess.SetState(net.StateAccountName)
			sess.Write("Account name: ")
		})
		return
	}
	// The account name comes from the race-free authName snapshot (set by
	// the owner when the password prompt was offered), NOT from
	// sess.Account: the owner goroutine can replace Account at any moment
	// (account republish after a rename/purge), and reading a plain field
	// the owner concurrently writes is a data race.
	name := sess.AuthName()
	if name == "" {
		// Defensive: password prompts only follow an account-name step.
		g.RunOnOwner(func() {
			if g.isShuttingDown() {
				return
			}
			g.handlePassword(sess, input)
		})
		return
	}
	auth := passwordAuth{}
	acc, err := g.AccountStore.LoadAccount(name)
	switch {
	case err != nil:
		auth.loadErr = true
	case player.CheckPassword(input, acc.PasswordHash):
		auth.ok, auth.stored = true, acc.PasswordHash
		// Transparent upgrade: legacy single-pass SHA-256 hashes rehash to
		// Argon2id after a successful verification. A failed rehash keeps
		// the legacy hash and retries on the next login.
		if player.NeedsRehash(acc.PasswordHash) {
			if hash, hashErr := player.HashPassword(input); hashErr == nil {
				auth.rehash = hash
			} else {
				log.Printf("login: password rehash for %s: %v", acc.Name, hashErr)
			}
		}
	}
	g.RunOnOwner(func() {
		if g.isShuttingDown() {
			return
		}
		g.applyPasswordAuth(sess, auth)
	})
}

// applyPasswordAuth completes (or rejects) a password login on the owner.
func (g *Game) applyPasswordAuth(sess *net.Session, auth passwordAuth) {
	sess.SetEcho(true)
	reject := func(message string) {
		sess.WriteLine(message)
		sess.SetState(net.StateAccountName)
		sess.Write("Account name: ")
	}
	if auth.loadErr {
		reject("Error loading account.")
		return
	}
	if !auth.ok {
		reject("Wrong password.")
		return
	}
	acc, err := g.AccountStore.LoadAccount(sess.Account.Name)
	if err != nil {
		reject("Error loading account.")
		return
	}
	if acc.PasswordHash != auth.stored {
		// The account changed while the hash was being verified (password
		// change, rename, or delete): the verified hash is stale.
		reject("Account changed; sign in again.")
		return
	}
	if auth.rehash != "" {
		acc.PasswordHash = auth.rehash
		g.saveAccount(acc)
	}
	sess.Account = &player.Account{
		Name:         acc.Name,
		PasswordHash: acc.PasswordHash,
		Characters:   acc.Characters,
		Aliases:      acc.Aliases,
		Colors:       acc.Colors,
		Options:      acc.Options,
		Admin:        acc.Admin,
	}
	if sess.Account.Aliases == nil {
		sess.Account.Aliases = make(map[string]string)
	}
	if sess.Account.Colors == nil {
		sess.Account.Colors = make(map[string]string)
	}
	if sess.Account.Options == nil {
		sess.Account.Options = make(map[string]any)
	}
	g.showMenu(sess)
}

func (g *Game) handleNewPass(sess *net.Session, input string) {
	input = strings.TrimSpace(input)
	if input == "" {
		sess.SetEcho(true)
		sess.Account = nil
		sess.SetState(net.StateAccountName)
		sess.Write("Account name: ")
		return
	}
	if verr := player.ValidPassword(input); verr != nil {
		sess.WriteLine(verr.Error())
		sess.Write("Choose password: ")
		return
	}
	sess.PendingPass = input
	sess.SetState(net.StateNewAccount)
	sess.Write("Confirm password: ")
}

func (g *Game) handleNewAccount(sess *net.Session, input string) {
	input = strings.TrimSpace(input)
	if input == "" {
		sess.SetEcho(true)
		sess.Account = nil
		sess.SetState(net.StateAccountName)
		sess.Write("Account name: ")
		return
	}
	if input != sess.PendingPass {
		sess.SetEcho(true)
		sess.WriteLine("Passwords do not match.")
		sess.Account = nil
		sess.SetState(net.StateAccountName)
		sess.Write("Account name: ")
		return
	}

	hash, err := player.HashPassword(input)
	g.applyNewAccount(sess, hash, err)
}

// handleNewAccountOffOwner hashes the confirmed password on the caller's
// connection goroutine (Argon2id is expensive) and submits one owner task
// for the existence re-check and save.
func (g *Game) handleNewAccountOffOwner(sess *net.Session, input string) {
	input = strings.TrimSpace(input)
	// Hash unconditionally on the connection goroutine (Argon2id is
	// expensive); the owner task below re-checks the empty/mismatch cases
	// against owner-owned session state, so PendingPass is never read off
	// the owner. A wasted hash only happens on the rare mismatched-confirm
	// path, where handleNewAccount's own validation rejects it without a
	// second hash.
	hash, hashErr := player.HashPassword(input)
	g.RunOnOwner(func() {
		if g.isShuttingDown() {
			return
		}
		if input == "" || input != sess.PendingPass {
			g.handleNewAccount(sess, input)
			return
		}
		g.applyNewAccount(sess, hash, hashErr)
	})
}

// applyNewAccount creates the account on the owner. The password was
// already hashed by the caller (off the owner where possible).
func (g *Game) applyNewAccount(sess *net.Session, hash string, hashErr error) {
	if hashErr != nil {
		sess.SetEcho(true)
		sess.WriteLine(fmt.Sprintf("Error creating account: %v", hashErr))
		sess.Account = nil
		sess.SetState(net.StateAccountName)
		sess.Write("Account name: ")
		return
	}

	// Re-check existence as part of the same owner step as the save. The
	// name was validated as new when it was typed, but another session (or
	// the admin API) may have created it in the meantime; saving without
	// this check would overwrite that account's password and characters.
	if _, findErr := g.AccountStore.FindAccount(sess.Account.Name); findErr == nil {
		sess.SetEcho(true)
		sess.Account = nil
		sess.SetState(net.StateAccountName)
		sess.WriteLine("That account name was just taken; please sign in instead.")
		sess.Write("Account name: ")
		return
	}

	acc := &player.Account{
		Name:         sess.Account.Name,
		PasswordHash: hash,
	}
	if err := g.AccountStore.SaveAccount(acc); err != nil {
		sess.SetEcho(true)
		sess.WriteLine(fmt.Sprintf("Error creating account: %v", err))
		sess.Account = nil
		sess.SetState(net.StateAccountName)
		sess.Write("Account name: ")
		return
	}

	sess.SetEcho(true)
	sess.Account = &player.Account{
		Name:         acc.Name,
		PasswordHash: acc.PasswordHash,
		Aliases:      make(map[string]string),
		Colors:       make(map[string]string),
		Options:      make(map[string]any),
	}
	sess.PendingPass = ""
	sess.SetState(net.StateColorChoice)
	sess.Write("\nShould I disable color? [y/N] ")
}

func (g *Game) handleColorChoice(sess *net.Session, input string) {
	input = strings.ToLower(strings.TrimSpace(input))
	if input == "y" || input == "yes" {
		sess.Account.Options["color"] = "none"
		acc, err := g.AccountStore.LoadAccount(sess.Account.Name)
		if err == nil {
			if acc.Options == nil {
				acc.Options = make(map[string]any)
			}
			acc.Options["color"] = "none"
			g.saveAccount(acc)
		}
	}
	g.showMenu(sess)
}

func menuColorMode(sess *net.Session) string {
	if sess != nil && sess.Account != nil && sess.Account.Options != nil {
		if v, ok := sess.Account.Options["color"]; ok {
			if s, ok := v.(string); ok && s != "" {
				return s
			}
		}
	}
	return "xterm256"
}

func (g *Game) showMenu(sess *net.Session) {
	sess.SetState(net.StateMenu)
	mode := menuColorMode(sess)
	lines := []string{
		"",
		fmt.Sprintf("Welcome back to Vesta, %s.", sess.Account.Name),
		"",
	}
	if len(sess.Account.Characters) > 0 {
		lines = append(lines,
			color.ExpandTags(mode, "   {03}(C){/}{04}onnect character to THOI{/}"),
			"",
			color.ExpandTags(mode, "   {03}(L){/}{04}ist characters{/}"),
			color.ExpandTags(mode, "   {03}(R){/}{04}ename character{/}"),
			color.ExpandTags(mode, "   {03}(D){/}{04}elete character{/}"),
		)
	}
	lines = append(lines,
		color.ExpandTags(mode, "   {03}(N){/}{04}ew character{/}"),
		color.ExpandTags(mode, "   {03}(P){/}{04}urge account{/}"),
		color.ExpandTags(mode, "   {03}(A){/}{04}ccount rename{/}"),
		color.ExpandTags(mode, "   {03}(Q){/}{04}uit{/}"),
		"",
	)
	sess.WriteLines(lines...)
	sess.Write("> ")
}

func (g *Game) handleMenu(sess *net.Session, input string) {
	switch strings.ToLower(strings.TrimSpace(input)) {
	case "":
		sess.Write("> ")
	case "c":
		if len(sess.Account.Characters) == 0 {
			sess.WriteLine("\nHey, make a character with 'N' first!")
			sess.Write("\n> ")
			return
		}
		if len(sess.Account.Characters) == 1 {
			g.connectCharacter(sess, sess.Account.Characters[0])
			return
		}
		sess.WriteLine("\nSelect character:")
		for i, name := range sess.Account.Characters {
			sess.WriteLine(fmt.Sprintf("  %d) %s", i+1, name))
		}
		sess.SetState(net.StateNewCharName)
		sess.PendingChar = "connect"
		sess.Write("\n> ")

	case "l":
		if len(sess.Account.Characters) == 0 {
			sess.WriteLine("\nYou don't have any characters! Make one with 'N'!")
		} else {
			sess.WriteLine("\nCharacters:")
			for _, name := range sess.Account.Characters {
				sess.WriteLine(fmt.Sprintf("  - %s", name))
			}
		}
		sess.Write("\n> ")

	case "n":
		sess.SetState(net.StateNewCharName)
		sess.PendingChar = ""
		sess.Write("What's your character name?: ")

	case "a":
		sess.SetState(net.StateRenameAccount)
		sess.Write("New account name: ")

	case "r":
		if len(sess.Account.Characters) == 0 {
			sess.WriteLine("\nRename who? You don't have any characters!")
			sess.Write("\n> ")
			return
		}
		if len(sess.Account.Characters) == 1 {
			sess.PendingChar = sess.Account.Characters[0]
			sess.SetState(net.StateRenameCharName)
			sess.WriteLine(fmt.Sprintf("\nRenaming %s.", sess.PendingChar))
			sess.Write("New name: ")
			return
		}
		sess.SetState(net.StateRenameChar)
		sess.WriteLine("\nRename which character?")
		for i, name := range sess.Account.Characters {
			sess.WriteLine(fmt.Sprintf("  %d) %s", i+1, name))
		}
		sess.Write("\n> ")

	case "d":
		if len(sess.Account.Characters) == 0 {
			sess.WriteLine("\nNo characters to delete.")
			sess.Write("\n> ")
			return
		}
		if len(sess.Account.Characters) == 1 {
			sess.PendingChar = sess.Account.Characters[0]
		} else {
			sess.SetState(net.StateDeleteChar)
			sess.WriteLine("\nDelete which character?")
			for i, name := range sess.Account.Characters {
				sess.WriteLine(fmt.Sprintf("  %d) %s", i+1, name))
			}
			sess.Write("\n> ")
			return
		}
		g.showDeleteConfirm(sess)

	case "p":
		sess.SetState(net.StatePurgeAccount)
		sess.WriteLine(fmt.Sprintf("\nPurge account %s and all characters?\nTo be clear you are about to PERMANENTLY DELETE EVERYTHING!\nType PURGE %s to confirm, or anything else to cancel.", sess.Account.Name, sess.Account.Name))
		sess.Write("\n> ")

	case "q":
		sess.WriteLine("Later.")
		sess.Close()
		return

	default:
		sess.Write("> ")
	}
}

func (g *Game) handleRenameAccount(sess *net.Session, input string) {
	newName := strings.TrimSpace(input)
	if newName == "" {
		sess.Write("New account name: ")
		return
	}
	if verr := player.ValidName(newName); verr != nil {
		sess.WriteLine(verr.Error())
		sess.Write("New account name: ")
		return
	}
	oldName := sess.Account.Name
	if newName == oldName {
		sess.WriteLine("That's already your account name.")
		g.showMenu(sess)
		return
	}
	if g.AccountStore.AccountExists(newName) {
		sess.WriteLine("An account with that name already exists.")
		sess.Write("New account name: ")
		return
	}

	// One journal transaction: file move + embedded name rewrite. Any
	// failure rolls back, so the account is never half-renamed.
	if err := g.renameAccountTxn(oldName, newName); err != nil {
		sess.WriteLine(fmt.Sprintf("Error renaming account: %v", err))
		g.showMenu(sess)
		return
	}

	// Republish account state to EVERY session of this account: other
	// authenticated sessions must not retain stale account objects or
	// pending menu selections bound to the old name. Stale sessions still
	// carry the old cached name, so match both.
	g.publishAccountUpdate(oldName, newName)

	sess.WriteLine(fmt.Sprintf("Account renamed to %s.", newName))
	g.showMenu(sess)
}

func (g *Game) handlePurgeAccount(sess *net.Session, input string) {
	input = strings.TrimSpace(input)
	expected := "PURGE " + sess.Account.Name
	if !strings.EqualFold(input, expected) {
		sess.WriteLine("Purge cancelled.")
		g.showMenu(sess)
		return
	}

	// Refuse to purge while any character is connected: a live session
	// would keep playing (and saving) a character whose file is about to
	// vanish. The online check and the purge run as one owner step, so no
	// connection can start a character between check and deletion.
	for _, name := range sess.Account.Characters {
		if g.characterOnline(name) {
			sess.WriteLine(fmt.Sprintf("%s is logged in. Log all characters out before purging.", name))
			g.showMenu(sess)
			return
		}
	}

	if err := g.purgeAccountTxn(sess.Account.Name, sess.Account.Characters); err != nil {
		sess.WriteLine(fmt.Sprintf("Error purging account: %v", err))
		g.showMenu(sess)
		return
	}

	sess.WriteLine(fmt.Sprintf("Account %s has been purged. Thanks for playing.", sess.Account.Name))
	// Other authenticated sessions of this account are stale now; tell
	// them and close them (they cannot safely keep using cached state).
	for _, other := range g.allSessionsOfAccount(sess.Account.Name) {
		if other == sess {
			continue
		}
		other.Account = nil
		other.PendingChar = ""
		other.PendingMenu = nil
		other.WriteLine("\nYour account has been purged from another session.")
		other.Close()
	}
	sess.Close()
}