package task

import (
	"time"
)

type State string

const (
	StatePending       State = "PENDING"
	StateQueued        State = "QUEUED"
	StateRunning       State = "RUNNING"
	StateReady         State = "READY"
	StateCompleted     State = "COMPLETED"
	StateFailed        State = "FAILED"
	StateTimedOut      State = "TIMED_OUT"
	StateCancelled     State = "CANCELLED"
	StateBudgetExceeded State = "BUDGET_EXCEEDED"
	StateBlocked        State = "BLOCKED"
)

type Priority string

const (
	PriorityHigh   Priority = "high"
	PriorityNormal Priority = "normal"
	PriorityLow    Priority = "low"
)

type AgentConfig struct {
	Type               string   `yaml:"type"               json:"type"`
	Model              string   `yaml:"model"               json:"model"`
	ContextFiles       []string `yaml:"context_files"       json:"context_files"`
	Instructions       string   `yaml:"instructions"        json:"instructions"`
	RepositoryURL      string   `yaml:"repository_url"      json:"repository_url"`
	ContainerImage     string   `yaml:"container_image"     json:"container_image"`
	ProjectDir         string   `yaml:"project_dir"         json:"project_dir"` // Deprecated: use Task.RepositoryURL
	MaxBudgetUSD       float64  `yaml:"max_budget_usd"      json:"max_budget_usd"`
	PermissionMode     string   `yaml:"permission_mode"     json:"permission_mode"`
	AllowedTools       []string `yaml:"allowed_tools"       json:"allowed_tools"`
	DisallowedTools    []string `yaml:"disallowed_tools"    json:"disallowed_tools"`
	SystemPromptAppend string   `yaml:"system_prompt_append" json:"system_prompt_append"`
	AdditionalArgs     []string `yaml:"additional_args"     json:"additional_args"`
	SkipPlanning       bool     `yaml:"skip_planning"       json:"skip_planning"`
}


type RetryConfig struct {
	MaxAttempts int    `yaml:"max_attempts" json:"max_attempts"`
	Backoff     string `yaml:"backoff"      json:"backoff"` // "linear", "exponential"
}

// GitCommit represents a single git commit created during a task execution.
type GitCommit struct {
	Hash    string `json:"hash"`
	Message string `json:"message"`
}

// Changestats records file/line change metrics from an agent execution.
type Changestats struct {
	FilesChanged int `json:"files_changed"`
	LinesAdded   int `json:"lines_added"`
	LinesRemoved int `json:"lines_removed"`
}

// Interaction records a single question/answer exchange between an agent and the user.
type Interaction struct {
	QuestionText string    `json:"question_text"`
	Options      []string  `json:"options,omitempty"`
	Answer       string    `json:"answer,omitempty"`
	AskedAt      time.Time `json:"asked_at"`
}

type Task struct {
	ID           string       `yaml:"id"            json:"id"`
	ParentTaskID string       `yaml:"parent_task_id" json:"parent_task_id"`
	Name         string       `yaml:"name"          json:"name"`
	Description  string       `yaml:"description"    json:"description"`
	Project      string       `yaml:"project"        json:"project"` // Human-readable project name
	RepositoryURL string      `yaml:"repository_url" json:"repository_url"`
	Agent        AgentConfig  `yaml:"agent"          json:"agent"`
	Timeout      Duration     `yaml:"timeout"        json:"timeout"`
	Retry        RetryConfig  `yaml:"retry"          json:"retry"`
	Priority    Priority     `yaml:"priority"   json:"priority"`
	Tags        []string     `yaml:"tags"       json:"tags"`
	DependsOn   []string     `yaml:"depends_on" json:"depends_on"`
	State             State         `yaml:"-"          json:"state"`
	RejectionComment  string        `yaml:"-"          json:"rejection_comment,omitempty"`
	QuestionJSON      string        `yaml:"-"          json:"question,omitempty"`
	ElaborationInput  string        `yaml:"-"          json:"elaboration_input,omitempty"`
	Summary           string        `yaml:"-"          json:"summary,omitempty"`
	Interactions      []Interaction `yaml:"-"          json:"interactions,omitempty"`
	CreatedAt         time.Time     `yaml:"-"          json:"created_at"`
	UpdatedAt         time.Time     `yaml:"-"          json:"updated_at"`
}

// Duration wraps time.Duration for YAML unmarshaling from strings like "30m".
type Duration struct {
	time.Duration
}

func (d *Duration) UnmarshalYAML(unmarshal func(interface{}) error) error {
	var s string
	if err := unmarshal(&s); err != nil {
		return err
	}
	dur, err := time.ParseDuration(s)
	if err != nil {
		return err
	}
	d.Duration = dur
	return nil
}

func (d Duration) MarshalYAML() (interface{}, error) {
	return d.Duration.String(), nil
}

// BatchFile represents a YAML file containing multiple tasks.
type BatchFile struct {
	Tasks []Task `yaml:"tasks"`
}

// validTransitions maps each state to the set of states it may transition into.
// COMPLETED is the only true terminal state (no outgoing edges).
// CANCELLED, FAILED, TIMED_OUT, and BUDGET_EXCEEDED all allow re-entry at QUEUED
// (restart or retry).
// READY may go back to PENDING on user rejection.
// BLOCKED may advance to READY when all subtasks complete, or back to QUEUED on user answer.
var validTransitions = map[State]map[State]bool{
	StatePending:        {StateQueued: true, StateCancelled: true},
	StateQueued:         {StateRunning: true, StateCancelled: true},
	StateRunning:        {StateReady: true, StateCompleted: true, StateFailed: true, StateTimedOut: true, StateCancelled: true, StateBudgetExceeded: true, StateBlocked: true},
	StateReady:          {StateCompleted: true, StatePending: true},
	StateFailed:         {StateQueued: true}, // retry
	StateTimedOut:       {StateQueued: true}, // retry or resume
	StateCancelled:      {StateQueued: true}, // restart
	StateBudgetExceeded: {StateQueued: true}, // retry
	StateBlocked:        {StateQueued: true, StateReady: true, StateCancelled: true},
}

// ValidTransition returns true if moving from the current state to next is allowed.
func ValidTransition(from, to State) bool {
	return validTransitions[from][to]
}