package coach

import (
	"encoding/json"
	"errors"
	"slices"
	"sort"
	"strings"
	"time"
)

var (
	ErrNotFound            = errors.New("growth coach: not found")
	ErrUnknownTerminal     = errors.New("growth coach: unknown terminal")
	ErrIdempotencyConflict = errors.New("growth coach: idempotency conflict")
	ErrInvalidTransition   = errors.New("growth coach: invalid transition")
	ErrInvalidCadence      = errors.New("growth coach: invalid refresh cadence")
	ErrRefreshLimited      = errors.New("growth coach: refresh limited")
)

type RefreshLimitError struct{ NextRefreshAt time.Time }

func (e *RefreshLimitError) Error() string {
	return "growth coach: refresh limited until " + e.NextRefreshAt.Format(time.RFC3339)
}

func (e *RefreshLimitError) Unwrap() error { return ErrRefreshLimited }

type RefreshInput struct {
	Cadence string `json:"cadence"`
}

func (r RefreshInput) Validate() error {
	if !ManualRefreshAllowed(r.Cadence, 0) {
		return ErrInvalidCadence
	}
	return nil
}

type ProfileInput struct {
	BusinessDescription string   `json:"businessDescription"`
	Niches              []string `json:"niches"`
	SalesChannels       []string `json:"salesChannels"`
	PrimaryGoal         string   `json:"primaryGoal"`
	Constraints         string   `json:"constraints"`
}

func (p ProfileInput) Validate() error {
	descriptionLength := len([]rune(strings.TrimSpace(p.BusinessDescription)))
	goalLength := len([]rune(strings.TrimSpace(p.PrimaryGoal)))
	if descriptionLength < 20 || descriptionLength > 2000 || goalLength < 3 || goalLength > 500 || len([]rune(p.Constraints)) > 1000 {
		return errors.New("growth coach: invalid profile text")
	}
	if len(p.Niches) < 1 || len(p.Niches) > 10 || len(p.SalesChannels) < 1 || len(p.SalesChannels) > 10 {
		return errors.New("growth coach: invalid profile selections")
	}
	for _, value := range append(append([]string{}, p.Niches...), p.SalesChannels...) {
		if length := len([]rune(strings.TrimSpace(value))); length < 1 || length > 80 {
			return errors.New("growth coach: invalid profile selection")
		}
	}
	return nil
}

type Profile struct {
	ProfileID  string `json:"profileId"`
	TerminalID string `json:"terminalId"`
	Version    int    `json:"version"`
	Difficulty int    `json:"difficulty"`
	ProfileInput
	CreatedAt     time.Time     `json:"createdAt"`
	ChangedFields []string      `json:"changedFields"`
	PreviousInput *ProfileInput `json:"-"`
}

func NormalizeProfileInput(input ProfileInput) ProfileInput {
	input.BusinessDescription = strings.Join(strings.Fields(input.BusinessDescription), " ")
	input.PrimaryGoal = strings.Join(strings.Fields(input.PrimaryGoal), " ")
	input.Constraints = strings.Join(strings.Fields(input.Constraints), " ")
	input.Niches = normalizeProfileList(input.Niches)
	input.SalesChannels = normalizeProfileList(input.SalesChannels)
	return input
}

func normalizeProfileList(values []string) []string {
	seen := map[string]struct{}{}
	result := make([]string, 0, len(values))
	for _, value := range values {
		value = strings.Join(strings.Fields(value), " ")
		if value == "" {
			continue
		}
		if _, ok := seen[value]; ok {
			continue
		}
		seen[value] = struct{}{}
		result = append(result, value)
	}
	sort.Strings(result)
	return result
}

func ChangedProfileFields(previous, next ProfileInput) []string {
	previous, next = NormalizeProfileInput(previous), NormalizeProfileInput(next)
	fields := []string{}
	if previous.BusinessDescription != next.BusinessDescription {
		fields = append(fields, "businessDescription")
	}
	if !slices.Equal(previous.Niches, next.Niches) {
		fields = append(fields, "niches")
	}
	if !slices.Equal(previous.SalesChannels, next.SalesChannels) {
		fields = append(fields, "salesChannels")
	}
	if previous.PrimaryGoal != next.PrimaryGoal {
		fields = append(fields, "primaryGoal")
	}
	if previous.Constraints != next.Constraints {
		fields = append(fields, "constraints")
	}
	return fields
}

type Recommendation struct {
	RecommendationID string              `json:"recommendationId"`
	PlanID           string              `json:"planId"`
	Rank             int                 `json:"rank"`
	Status           string              `json:"status"`
	ActionType       string              `json:"actionType"`
	Title            string              `json:"title"`
	Rationale        string              `json:"rationale"`
	ExpectedImpact   string              `json:"expectedImpact"`
	Effort           string              `json:"effort"`
	EvidenceIDs      []string            `json:"evidenceIds"`
	MetricID         *string             `json:"metricId,omitempty"`
	MetricDirection  *string             `json:"metricDirection,omitempty"`
	ActionLevel      *string             `json:"actionLevel,omitempty"`
	Baseline         *float64            `json:"baseline,omitempty"`
	Target           *float64            `json:"target,omitempty"`
	SampleSize       int64               `json:"sampleSize"`
	Deadline         string              `json:"deadline"`
	Subtasks         []GenerationSubtask `json:"subtasks"`
	EventIDs         []string            `json:"eventIds"`
}

type Plan struct {
	PlanID      string           `json:"planId"`
	ParentID    *string          `json:"parentId,omitempty"`
	Cadence     string           `json:"cadence"`
	Status      string           `json:"status"`
	PeriodStart string           `json:"periodStart"`
	PeriodEnd   string           `json:"periodEnd"`
	DailyBrief  *string          `json:"dailyBrief,omitempty"`
	Difficulty  int              `json:"difficulty"`
	Suggestions []Recommendation `json:"suggestions"`
	GeneratedAt time.Time        `json:"generatedAt"`
}

type Action struct {
	ActionID         string    `json:"actionId"`
	RecommendationID string    `json:"recommendationId"`
	TerminalID       string    `json:"terminalId"`
	ActionType       string    `json:"actionType"`
	Title            string    `json:"title"`
	Status           string    `json:"status"`
	MetricID         *string   `json:"metricId,omitempty"`
	MetricDirection  *string   `json:"metricDirection,omitempty"`
	Baseline         *float64  `json:"baseline,omitempty"`
	Target           *float64  `json:"target,omitempty"`
	CurrentValue     *float64  `json:"currentValue,omitempty"`
	SampleSize       int64     `json:"sampleSize"`
	Deadline         string    `json:"deadline"`
	UpdatedAt        time.Time `json:"updatedAt"`
}

type TerminalRollup struct {
	TerminalID       string  `json:"terminalId"`
	OnboardingStatus string  `json:"onboardingStatus"`
	ActiveActions    int     `json:"activeActions"`
	OverdueActions   int     `json:"overdueActions"`
	CompletionRate   float64 `json:"completionRate"`
}

type Dashboard struct {
	Scope               string               `json:"scope"`
	TerminalID          *string              `json:"terminalId,omitempty"`
	DataThrough         *string              `json:"dataThrough,omitempty"`
	GenerationState     string               `json:"generationState"`
	Profile             *Profile             `json:"profile,omitempty"`
	Plans               []Plan               `json:"plans"`
	Actions             []Action             `json:"actions"`
	Terminals           []TerminalRollup     `json:"terminals"`
	DifficultyProposals []DifficultyProposal `json:"difficultyProposals"`
}

type Job struct {
	JobID     string    `json:"jobId"`
	State     string    `json:"state"`
	EventsURL string    `json:"eventsUrl"`
	CreatedAt time.Time `json:"createdAt"`
	UpdatedAt time.Time `json:"updatedAt"`
}

type Event struct {
	ID         int64           `json:"eventId"`
	Type       string          `json:"type"`
	Payload    json.RawMessage `json:"payload"`
	OccurredAt time.Time       `json:"occurredAt"`
}

type DecisionInput struct {
	Decision string `json:"decision"`
	Reason   string `json:"reason"`
	Note     string `json:"note"`
}

type TransitionInput struct {
	Transition string `json:"transition"`
}

type DifficultyProposal struct {
	ProposalID string `json:"proposalId"`
	FromLevel  int    `json:"fromLevel"`
	ToLevel    int    `json:"toLevel"`
	Reason     string `json:"reason"`
	Status     string `json:"status"`
}

type GenerationSuggestion struct {
	ActionType      string              `json:"actionType"`
	Title           string              `json:"title"`
	Rationale       string              `json:"rationale"`
	ExpectedImpact  string              `json:"expectedImpact"`
	Effort          string              `json:"effort"`
	EvidenceIDs     []string            `json:"evidenceIds"`
	MetricID        *string             `json:"metricId"`
	MetricDirection *string             `json:"metricDirection"`
	ActionLevel     *string             `json:"actionLevel"`
	Subtasks        []GenerationSubtask `json:"subtasks"`
	EventIDs        []string            `json:"eventIds"`
}

type GenerationSubtask struct {
	Title    string  `json:"title"`
	Deadline *string `json:"deadline"`
	EventID  *string `json:"eventId"`
}

type GoalSubtask struct {
	SubtaskID   string     `json:"subtaskId"`
	Position    int        `json:"position"`
	Title       string     `json:"title"`
	Status      string     `json:"status"`
	Deadline    string     `json:"deadline"`
	EventID     *string    `json:"eventId,omitempty"`
	CompletedAt *time.Time `json:"completedAt,omitempty"`
}

type MonthlyGoal struct {
	GoalID            string             `json:"goalId"`
	RecommendationID  string             `json:"recommendationId"`
	TerminalID        string             `json:"terminalId"`
	Title             string             `json:"title"`
	ExpectedImpact    string             `json:"expectedImpact"`
	Status            string             `json:"status"`
	MetricID          string             `json:"metricId"`
	MetricDirection   string             `json:"metricDirection"`
	Baseline          float64            `json:"baseline"`
	Target            float64            `json:"target"`
	CurrentValue      float64            `json:"currentValue"`
	ProgressPercent   float64            `json:"progressPercent"`
	SampleSize        int64              `json:"sampleSize"`
	Deadline          string             `json:"deadline"`
	EventIDs          []string           `json:"eventIds"`
	Subtasks          []GoalSubtask      `json:"subtasks"`
	DeadlineProposals []DeadlineProposal `json:"deadlineProposals"`
	UpdatedAt         time.Time          `json:"updatedAt"`
}

type SubtaskTransitionInput struct {
	Transition string `json:"transition"`
}

type DeadlineProposal struct {
	ProposalID       string     `json:"proposalId"`
	GoalID           string     `json:"goalId"`
	SubtaskID        string     `json:"subtaskId"`
	EventID          string     `json:"eventId"`
	CurrentDeadline  string     `json:"currentDeadline"`
	ProposedDeadline string     `json:"proposedDeadline"`
	Reason           string     `json:"reason"`
	Status           string     `json:"status"`
	DecidedAt        *time.Time `json:"decidedAt,omitempty"`
}

type DeadlineDecisionInput struct {
	Decision string `json:"decision"`
}

type Generation struct {
	DailyBrief  string                 `json:"dailyBrief"`
	Suggestions []GenerationSuggestion `json:"suggestions"`
}

type ProviderUsage struct {
	InputTokens       int64
	OutputTokens      int64
	ProviderRequests  int64
	LatencyMS         int64
	ProviderRequestID string
	EstimatedCost     string
}

type MetricEvidence struct {
	Sessions               int64              `json:"sessions"`
	Values                 map[string]float64 `json:"values"`
	EvidenceIDs            []string           `json:"evidenceIds"`
	DataThrough            string             `json:"dataThrough"`
	RecentDecisions        []CoachMemoryItem  `json:"recentDecisions"`
	RecentOutcomes         []CoachMemoryItem  `json:"recentOutcomes"`
	HasAcceptedMonthlyGoal bool               `json:"hasAcceptedMonthlyGoal"`
	Industry               string             `json:"industry"`
	RelevantEvents         []CoachEvent       `json:"relevantEvents"`
}

type CoachEvent struct {
	EventID   string `json:"eventId"`
	Title     string `json:"title"`
	StartDate string `json:"startDate"`
	EndDate   string `json:"endDate"`
	Reason    string `json:"reason"`
}

type CoachMemoryItem struct {
	Title  string `json:"title"`
	Status string `json:"status"`
	Reason string `json:"reason,omitempty"`
}