package repository

import (
	"database/sql"
	"errors"
	"fmt"

	"github.com/go-sql-driver/mysql"

	"cmautobuy/admin/model"
)

var (
	// ErrPurchaseSpecResolutionExists 表示解析编号或业务身份已经存在，调用方应读取旧记录复查。
	ErrPurchaseSpecResolutionExists = errors.New("采购运行时规格解析记录已存在")
	// ErrPurchaseSpecResolutionConflict 表示相同业务身份对应了不同请求内容。
	ErrPurchaseSpecResolutionConflict = errors.New("采购运行时规格解析请求冲突")
	// ErrPurchaseSpecResolutionNotFound 表示要完成的解析记录不存在。
	ErrPurchaseSpecResolutionNotFound = errors.New("采购运行时规格解析记录不存在")
	// ErrPurchaseSpecResolutionCompleted 表示解析记录已经完成，不能覆盖第一次决策。
	ErrPurchaseSpecResolutionCompleted = errors.New("采购运行时规格解析记录已经完成")
)

// InsertPurchaseSpecResolution 保存一次候选观察。匹配逻辑不在 Repository 中执行。
func InsertPurchaseSpecResolution(q Execer, resolution model.PurchaseSpecResolution) error {
	if resolution.Outcome == "" {
		resolution.Outcome = model.PurchaseSpecResolutionPending
	}
	_, err := q.Exec(`INSERT INTO purchase_spec_resolutions
		(resolution_id,task_id,attempt_id,client_id,task_version,pdd_goods_id,
		 original_options_json,selected_color,target_size,candidates_json,candidate_snapshot_hash,
		 request_hash,observed_at,outcome,created_at)
		VALUES(?,?,?,?,?,?,?,?,?,?,?,?,?,?,?)`,
		resolution.ResolutionID, resolution.TaskID, resolution.AttemptID, resolution.ClientID,
		resolution.TaskVersion, resolution.PddGoodsID, resolution.OriginalOptionsJSON,
		resolution.SelectedColor, resolution.TargetSize, resolution.CandidatesJSON,
		resolution.CandidateSnapshotHash, resolution.RequestHash, resolution.ObservedAt,
		resolution.Outcome, resolution.CreatedAt)
	if err == nil {
		return nil
	}
	var mysqlErr *mysql.MySQLError
	if errors.As(err, &mysqlErr) && mysqlErr.Number == 1062 {
		return ErrPurchaseSpecResolutionExists
	}
	return fmt.Errorf("写入采购运行时规格解析观察失败: %w", err)
}

// GetPurchaseSpecResolutionByID 按公开解析编号读取候选观察和最终决策。
func GetPurchaseSpecResolutionByID(q Execer, resolutionID string) (*model.PurchaseSpecResolution, error) {
	return scanPurchaseSpecResolution(q.QueryRow(purchaseSpecResolutionSelect+` WHERE resolution_id=?`, resolutionID))
}

// GetPurchaseSpecResolutionByIdentity 按任务、执行尝试和候选快照读取唯一解析记录。
func GetPurchaseSpecResolutionByIdentity(q Execer, taskID, attemptID, candidateSnapshotHash string) (*model.PurchaseSpecResolution, error) {
	return scanPurchaseSpecResolution(q.QueryRow(purchaseSpecResolutionSelect+
		` WHERE task_id=? AND attempt_id=? AND candidate_snapshot_hash=?`,
		taskID, attemptID, candidateSnapshotHash))
}

// GetPurchaseSpecResolutionForReplay 复查幂等重放。相同业务身份但请求哈希不同必须冲突。
func GetPurchaseSpecResolutionForReplay(q Execer, taskID, attemptID, candidateSnapshotHash, requestHash string) (*model.PurchaseSpecResolution, error) {
	resolution, err := GetPurchaseSpecResolutionByIdentity(q, taskID, attemptID, candidateSnapshotHash)
	if err != nil || resolution == nil {
		return resolution, err
	}
	if resolution.RequestHash != requestHash {
		return nil, ErrPurchaseSpecResolutionConflict
	}
	return resolution, nil
}

// CompletePurchaseSpecResolution 只允许把 pending 记录完成一次，保留第一次决策审计。
func CompletePurchaseSpecResolution(q Execer, decision model.PurchaseSpecResolutionDecision) error {
	result, err := q.Exec(`UPDATE purchase_spec_resolutions SET
		outcome=?,decision_source=?,chosen_candidate_id=?,resolved_options_json=?,confidence_bps=?,
		reason=?,provider_id=?,source_model=?,config_fingerprint=?,rules_version=?,prompt_version=?,decided_at=?
		WHERE resolution_id=? AND outcome='pending'`,
		decision.Outcome, nullableText(string(decision.DecisionSource)), nullableText(decision.ChosenCandidateID),
		nullableText(decision.ResolvedOptionsJSON), nullableInt(decision.ConfidenceBPS, decision.ConfidenceSet),
		nullableText(decision.Reason), nullableText(decision.ProviderID), nullableText(decision.SourceModel),
		nullableText(decision.ConfigFingerprint), nullableText(decision.RulesVersion), nullableText(decision.PromptVersion),
		decision.DecidedAt, decision.ResolutionID)
	if err != nil {
		return fmt.Errorf("完成采购运行时规格解析失败: %w", err)
	}
	affected, err := result.RowsAffected()
	if err != nil {
		return fmt.Errorf("读取采购运行时规格解析更新结果失败: %w", err)
	}
	if affected == 1 {
		return nil
	}
	existing, err := GetPurchaseSpecResolutionByID(q, decision.ResolutionID)
	if err != nil {
		return err
	}
	if existing == nil {
		return ErrPurchaseSpecResolutionNotFound
	}
	return ErrPurchaseSpecResolutionCompleted
}

const purchaseSpecResolutionSelect = `SELECT
	resolution_id,task_id,attempt_id,client_id,task_version,pdd_goods_id,
	original_options_json,selected_color,target_size,candidates_json,candidate_snapshot_hash,
	request_hash,observed_at,outcome,decision_source,chosen_candidate_id,resolved_options_json,
	confidence_bps,reason,provider_id,source_model,config_fingerprint,rules_version,prompt_version,
	created_at,decided_at FROM purchase_spec_resolutions`

func scanPurchaseSpecResolution(row *sql.Row) (*model.PurchaseSpecResolution, error) {
	var resolution model.PurchaseSpecResolution
	var source, candidateID, resolvedOptions, reason, providerID sql.NullString
	var sourceModel, configFingerprint, rulesVersion, promptVersion, decidedAt sql.NullString
	var confidence sql.NullInt64
	err := row.Scan(
		&resolution.ResolutionID, &resolution.TaskID, &resolution.AttemptID, &resolution.ClientID,
		&resolution.TaskVersion, &resolution.PddGoodsID, &resolution.OriginalOptionsJSON,
		&resolution.SelectedColor, &resolution.TargetSize, &resolution.CandidatesJSON,
		&resolution.CandidateSnapshotHash, &resolution.RequestHash, &resolution.ObservedAt,
		&resolution.Outcome, &source, &candidateID, &resolvedOptions, &confidence, &reason,
		&providerID, &sourceModel, &configFingerprint, &rulesVersion, &promptVersion,
		&resolution.CreatedAt, &decidedAt)
	if errors.Is(err, sql.ErrNoRows) {
		return nil, nil
	}
	if err != nil {
		return nil, fmt.Errorf("读取采购运行时规格解析失败: %w", err)
	}
	resolution.DecisionSource = model.PurchaseSpecResolutionSource(source.String)
	resolution.ChosenCandidateID = candidateID.String
	resolution.ResolvedOptionsJSON = resolvedOptions.String
	resolution.ConfidenceBPS = int(confidence.Int64)
	resolution.ConfidenceSet = confidence.Valid
	resolution.Reason = reason.String
	resolution.ProviderID = providerID.String
	resolution.SourceModel = sourceModel.String
	resolution.ConfigFingerprint = configFingerprint.String
	resolution.RulesVersion = rulesVersion.String
	resolution.PromptVersion = promptVersion.String
	resolution.DecidedAt = decidedAt.String
	return &resolution, nil
}