package model

import (
	"encoding/json"
	"net/url"
	"regexp"
	"strings"
	"time"
	"unicode/utf8"

	"git.sundynix.cn/Blizzard/Veyra/internal/apperror"
)

type Candidate struct {
	ID                  string    `db:"id" json:"id"`
	LatestRevision      int       `db:"latest_revision" json:"latest_revision"`
	PublishedRevisionID *string   `db:"published_revision_id" json:"published_revision_id"`
	CreatedAt           time.Time `db:"created_at" json:"created_at"`
}

func (Candidate) TableName() string { return "veyra_candidate" }

type CandidateEvidence struct {
	SourceURL string `json:"source_url"`
	Locator   string `json:"locator"`
	Summary   string `json:"summary"`
}
type CandidateReferencePlan struct {
	EntryLow    string `json:"entry_low"`
	EntryHigh   string `json:"entry_high"`
	StopLoss    string `json:"stop_loss"`
	TargetPrice string `json:"target_price"`
}
type CandidateContent struct {
	Symbol          string                 `json:"symbol"`
	Exchange        string                 `json:"exchange"`
	Name            string                 `json:"name"`
	StrategyCode    string                 `json:"strategy_code"`
	Title           string                 `json:"title"`
	Thesis          string                 `json:"thesis"`
	Evidence        []CandidateEvidence    `json:"evidence"`
	CounterEvidence string                 `json:"counter_evidence"`
	Invalidation    string                 `json:"invalidation"`
	ReferencePlan   CandidateReferencePlan `json:"reference_plan"`
}

type CandidateRevision struct {
	AIAnalysis          *CandidateAnalysis `json:"ai_analysis,omitempty"`
	Screening           *StrategyScreening `json:"screening,omitempty"`
	ID                  string             `db:"id" json:"id"`
	CandidateID         string             `db:"candidate_id" json:"candidate_id"`
	Revision            int                `db:"revision" json:"revision"`
	Version             int64              `db:"version" json:"version"`
	Status              string             `db:"status" json:"status"`
	DataMode            string             `db:"data_mode" json:"data_mode"`
	Snapshot            CandidateContent   `db:"snapshot" json:"content"`
	AuthorID            string             `db:"author_id" json:"author_id"`
	ObservedAt          time.Time          `db:"observed_at" json:"observed_at"`
	ValidUntil          time.Time          `db:"valid_until" json:"valid_until"`
	PublishedAt         *time.Time         `db:"published_at" json:"published_at"`
	CreatedAt           time.Time          `db:"created_at" json:"created_at"`
	UpdatedAt           time.Time          `db:"updated_at" json:"updated_at"`
	IsLatest            bool               `json:"is_latest"`
	WithdrawalReason    string             `json:"withdrawal_reason"`
	IsActivePublication bool               `json:"is_active_publication"`
}

func (CandidateRevision) TableName() string { return "veyra_candidate_revision" }

type CandidateReview struct {
	ID           string    `db:"id" json:"id"`
	RevisionID   string    `db:"revision_id" json:"revision_id"`
	ReviewerID   string    `db:"reviewer_id" json:"reviewer_id"`
	Decision     string    `db:"decision" json:"decision"`
	InputVersion int64     `db:"input_version" json:"input_version"`
	Reason       string    `db:"reason" json:"reason"`
	CreatedAt    time.Time `db:"created_at" json:"created_at"`
}

func (CandidateReview) TableName() string { return "veyra_candidate_review" }

type CandidateDraftInput struct {
	Content    CandidateContent `json:"content"`
	ObservedAt time.Time        `json:"observed_at"`
	ValidUntil time.Time        `json:"valid_until"`
}
type CandidateRevisionInput struct {
	CandidateDraftInput
	ExpectedVersion int64 `json:"expected_version"`
}
type CandidateActionInput struct {
	ExpectedVersion int64  `json:"expected_version"`
	Reason          string `json:"reason"`
}
type CandidateDetail struct {
	CandidateRevision
	Reviews []CandidateReview `json:"reviews"`
}

var symbolPattern = regexp.MustCompile(`^[0-9]{6}$`)

func textValid(s string, max int) bool {
	return strings.TrimSpace(s) != "" && utf8.RuneCountInString(s) <= max
}

func ValidateDraft(input CandidateDraftInput, now time.Time) error {
	c := input.Content
	if !symbolPattern.MatchString(c.Symbol) || c.Exchange != "SSE" && c.Exchange != "SZSE" || !textValid(c.Name, 80) || !textValid(c.Title, 120) || !textValid(c.Thesis, 2000) || !textValid(c.CounterEvidence, 1000) || !textValid(c.Invalidation, 1000) {
		return apperror.ErrInvalidInput
	}
	switch c.StrategyCode {
	case "trend_following", "pullback", "event_driven":
	default:
		return apperror.ErrInvalidInput
	}
	if len(c.Evidence) < 1 || len(c.Evidence) > 8 {
		return apperror.ErrInvalidInput
	}
	for _, e := range c.Evidence {
		u, err := url.Parse(e.SourceURL)
		if err != nil || u.Scheme != "https" || u.Hostname() == "" || u.User != nil || len(e.SourceURL) > 2048 || !textValid(e.Locator, 200) || !textValid(e.Summary, 1000) {
			return apperror.ErrInvalidInput
		}
	}
	low, e1 := ParseMoney(c.ReferencePlan.EntryLow)
	high, e2 := ParseMoney(c.ReferencePlan.EntryHigh)
	stop, e3 := ParseMoney(c.ReferencePlan.StopLoss)
	target, e4 := ParseMoney(c.ReferencePlan.TargetPrice)
	if e1 != nil || e2 != nil || e3 != nil || e4 != nil || stop <= 0 || stop >= low || low > high || target <= high {
		return apperror.ErrInvalidInput
	}
	if input.ObservedAt.IsZero() || input.ObservedAt.After(now.Add(time.Minute)) || input.ObservedAt.Before(now.Add(-24*time.Hour)) || !input.ValidUntil.After(now) || input.ValidUntil.After(now.Add(7*24*time.Hour)) || !input.ValidUntil.After(input.ObservedAt) {
		return apperror.ErrInvalidInput
	}
	encoded, err := json.Marshal(c)
	if err != nil || len(encoded) > 12<<10 {
		return apperror.ErrInvalidInput
	}
	return nil
}

// NextStatus is the shared state rule; repositories recheck it under the aggregate lock.
func NextStatus(r CandidateRevision, action string, now time.Time) (string, error) {
	if action == "WITHDRAW" {
		if r.Status != "PUBLISHED" || !r.IsActivePublication {
			return "", apperror.ErrConflict
		}
		return "WITHDRAWN", nil
	}
	if !r.IsLatest {
		return "", apperror.ErrConflict
	}
	switch action {
	case "SUBMIT":
		if r.Status != "DRAFT" {
			return "", apperror.ErrConflict
		}
		if err := ValidateDraft(CandidateDraftInput{Content: r.Snapshot, ObservedAt: r.ObservedAt, ValidUntil: r.ValidUntil}, now); err != nil {
			return "", apperror.ErrInvalidInput
		}
		return "PENDING_REVIEW", nil
	case "PUBLISH":
		if r.Status != "PENDING_REVIEW" {
			return "", apperror.ErrConflict
		}
		if err := ValidateDraft(CandidateDraftInput{Content: r.Snapshot, ObservedAt: r.ObservedAt, ValidUntil: r.ValidUntil}, now); err != nil {
			return "", apperror.ErrInvalidInput
		}
		return "PUBLISHED", nil
	case "RETURN":
		if r.Status != "PENDING_REVIEW" {
			return "", apperror.ErrConflict
		}
		return "RETURNED", nil
	default:
		return "", apperror.ErrInvalidInput
	}
}

func ValidateReason(reason string) error {
	if !textValid(reason, 1000) {
		return apperror.ErrInvalidInput
	}
	return nil
}