// Package session provides polecat session lifecycle management.
package session

import (
	"fmt"
	"strings"
)

// Role represents the type of Gas Town agent.
type Role string

const (
	RoleMayor    Role = "mayor"
	RoleDeacon   Role = "deacon"
	RoleWitness  Role = "witness"
	RoleRefinery Role = "refinery"
	RoleCrew     Role = "crew"
	RolePolecat  Role = "polecat"
)

// AgentIdentity represents a parsed Gas Town agent identity.
type AgentIdentity struct {
	Role Role   // mayor, deacon, witness, refinery, crew, polecat
	Rig  string // rig name (empty for mayor/deacon)
	Name string // crew/polecat name (empty for mayor/deacon/witness/refinery)
}

// ParseSessionName parses a tmux session name into an AgentIdentity.
//
// Session name formats:
//   - hq-mayor → Role: mayor (town-level, one per machine)
//   - hq-deacon → Role: deacon (town-level, one per machine)
//   - gt-<rig>-witness → Role: witness, Rig: <rig>
//   - gt-<rig>-refinery → Role: refinery, Rig: <rig>
//   - gt-<rig>-crew-<name> → Role: crew, Rig: <rig>, Name: <name>
//   - gt-<rig>-<name> → Role: polecat, Rig: <rig>, Name: <name>
//
// For polecat sessions without a crew marker, the last segment after the rig
// is assumed to be the polecat name. This works for simple rig names but may
// be ambiguous for rig names containing hyphens.
func ParseSessionName(session string) (*AgentIdentity, error) {
	// Check for town-level roles (hq- prefix)
	if strings.HasPrefix(session, HQPrefix) {
		suffix := strings.TrimPrefix(session, HQPrefix)
		if suffix == "mayor" {
			return &AgentIdentity{Role: RoleMayor}, nil
		}
		if suffix == "deacon" {
			return &AgentIdentity{Role: RoleDeacon}, nil
		}
		return nil, fmt.Errorf("invalid session name %q: unknown hq- role", session)
	}

	// Rig-level roles use gt- prefix
	if !strings.HasPrefix(session, Prefix) {
		return nil, fmt.Errorf("invalid session name %q: missing %q or %q prefix", session, HQPrefix, Prefix)
	}

	suffix := strings.TrimPrefix(session, Prefix)
	if suffix == "" {
		return nil, fmt.Errorf("invalid session name %q: empty after prefix", session)
	}

	// Parse into parts for rig-level roles
	parts := strings.Split(suffix, "-")
	if len(parts) < 2 {
		return nil, fmt.Errorf("invalid session name %q: expected rig-role format", session)
	}

	// Check for witness/refinery (suffix markers)
	if parts[len(parts)-1] == "witness" {
		rig := strings.Join(parts[:len(parts)-1], "-")
		return &AgentIdentity{Role: RoleWitness, Rig: rig}, nil
	}
	if parts[len(parts)-1] == "refinery" {
		rig := strings.Join(parts[:len(parts)-1], "-")
		return &AgentIdentity{Role: RoleRefinery, Rig: rig}, nil
	}

	// Check for crew (marker in middle)
	for i, p := range parts {
		if p == "crew" && i > 0 && i < len(parts)-1 {
			rig := strings.Join(parts[:i], "-")
			name := strings.Join(parts[i+1:], "-")
			return &AgentIdentity{Role: RoleCrew, Rig: rig, Name: name}, nil
		}
	}

	// Default to polecat: rig is everything except the last segment
	if len(parts) < 2 {
		return nil, fmt.Errorf("invalid session name %q: cannot determine rig/name", session)
	}
	rig := strings.Join(parts[:len(parts)-1], "-")
	name := parts[len(parts)-1]
	return &AgentIdentity{Role: RolePolecat, Rig: rig, Name: name}, nil
}

// SessionName returns the tmux session name for this identity.
func (a *AgentIdentity) SessionName() string {
	switch a.Role {
	case RoleMayor:
		return MayorSessionName()
	case RoleDeacon:
		return DeaconSessionName()
	case RoleWitness:
		return WitnessSessionName(a.Rig)
	case RoleRefinery:
		return RefinerySessionName(a.Rig)
	case RoleCrew:
		return CrewSessionName(a.Rig, a.Name)
	case RolePolecat:
		return PolecatSessionName(a.Rig, a.Name)
	default:
		return ""
	}
}

// Address returns the mail-style address for this identity.
// Examples:
//   - mayor → "mayor"
//   - deacon → "deacon"
//   - witness → "gastown/witness"
//   - refinery → "gastown/refinery"
//   - crew → "gastown/crew/max"
//   - polecat → "gastown/polecats/Toast"
func (a *AgentIdentity) Address() string {
	switch a.Role {
	case RoleMayor:
		return "mayor"
	case RoleDeacon:
		return "deacon"
	case RoleWitness:
		return fmt.Sprintf("%s/witness", a.Rig)
	case RoleRefinery:
		return fmt.Sprintf("%s/refinery", a.Rig)
	case RoleCrew:
		return fmt.Sprintf("%s/crew/%s", a.Rig, a.Name)
	case RolePolecat:
		return fmt.Sprintf("%s/polecats/%s", a.Rig, a.Name)
	default:
		return ""
	}
}

// GTRole returns the GT_ROLE environment variable format.
// This is the same as Address() for most roles.
func (a *AgentIdentity) GTRole() string {
	return a.Address()
}
