package postgres

import (
	"context"
	"encoding/json"
	"errors"
)

type MonitorTaskFilter struct {
	Search, Source, Scope, Action, Status, Stage, ID, Target, Since, Until string
	Limit, Offset                                                          int
}
type MonitorTaskEvent struct {
	At     string `json:"at"`
	Kind   string `json:"kind"`
	Detail string `json:"detail"`
}
type MonitorTask struct {
	History     []MonitorTaskEvent `json:"history"`
	ID          string             `json:"id"`
	Title       string             `json:"title"`
	Path        string             `json:"path"`
	SourceID    string             `json:"source_id"`
	SourceName  string             `json:"source_name"`
	TargetScope string             `json:"target_scope"`
	TargetKB    string             `json:"target_kb"`
	Action      string             `json:"action"`
	Stage       string             `json:"stage"`
	Status      string             `json:"status"`
	Detail      string             `json:"detail"`
	UpdatedAt   string             `json:"updated_at"`
	RetryKind   string             `json:"retry_kind"`
	FailureID   string             `json:"failure_id"`
	RetryCount  int                `json:"retry_count"`
	VersionID   string             `json:"version_id"`
}
type MonitorTaskPage struct {
	Items     []MonitorTask   `json:"items"`
	Total     int             `json:"total"`
	Limit     int             `json:"limit"`
	Offset    int             `json:"offset"`
	Sources   []MonitorOption `json:"sources"`
	Targets   []MonitorOption `json:"targets"`
	Retryable int             `json:"retryable"`
}
type MonitorOption struct {
	ID   string `json:"id"`
	Name string `json:"name"`
}

// Reduce publication versions before filtering; totals and pages share one snapshot.
const monitorTasksCTE = `WITH history_publications AS (
 SELECT hp.* FROM test_publications hp JOIN source_item_versions hv ON hv.id=hp.source_item_version_id
 WHERE $7<>'' AND (hv.source_item_id,hp.test_kb_id)=(SELECT v.source_item_id,p.test_kb_id FROM test_publications p JOIN source_item_versions v ON v.id=p.source_item_version_id WHERE p.id=$7)
), history_events AS (
 SELECT updated_at AS at,'版本状态' AS kind,source_item_version_id || ' · ' || processing_state || ' / ' || retrieval_state AS detail FROM history_publications
 UNION ALL SELECT f.created_at,'失败记录',f.job_type || ' · ' || f.error_code || ' · 尝试 ' || f.attempt FROM job_failures f LEFT JOIN jobs fj ON fj.id=f.job_id WHERE f.publication_id IN(SELECT id FROM history_publications) OR (f.job_type='artifact.fetch' AND COALESCE(NULLIF(f.business_version_id,''),fj.payload->>'version_id') IN(SELECT source_item_version_id FROM history_publications))
 UNION ALL SELECT r.created_at,'重试记录',r.reason || ' · ' || r.outcome FROM job_retry_operations r WHERE r.publication_id IN(SELECT id FROM history_publications)
), latest AS (
 SELECT DISTINCT ON(v.source_item_id,p.test_kb_id) p.*,v.source_item_id,v.content_object_id
 FROM test_publications p JOIN source_item_versions v ON v.id=p.source_item_version_id
 WHERE p.superseded_at IS NULL
 ORDER BY v.source_item_id,p.test_kb_id,p.created_at DESC,p.id DESC
), base AS (
 SELECT p.id,si.title,si.normalized_path AS path,c.id AS source_id,c.name AS source_name,
 p.target_scope,p.test_kb_id AS target_kb,p.source_item_version_id AS version_id,p.retry_count,
 GREATEST(p.updated_at,j.updated_at,f.created_at) AS updated_at,
 p.processing_state,p.ingest_state,p.retrieval_state,p.last_error,p.knowledge_id,
 co.content_state,co.local_spool_ref,si.policy_state,
 CASE WHEN p.retrieval_state IN ('disabling','disabled') OR (p.knowledge_id<>'' AND si.policy_state='blocked') OR j.type='test.remove' THEN 'remove'
 WHEN EXISTS(SELECT 1 FROM test_publications prev JOIN source_item_versions pv ON pv.id=prev.source_item_version_id WHERE pv.source_item_id=si.id AND prev.test_kb_id=p.test_kb_id AND prev.id<>p.id AND prev.created_at<p.created_at) THEN 'update' ELSE 'add' END AS action,
 COALESCE(j.type,'') AS job_type,COALESCE(j.state,'') AS job_state,COALESCE(j.attempt,0) AS job_attempt,j.available_at,
 COALESCE(f.id,'') AS failure_id,COALESCE(f.job_type,'') AS failure_type,COALESCE(NULLIF(f.last_error,''),f.error_code,'') AS failure_error
 FROM latest p JOIN source_items si ON si.id=p.source_item_id JOIN source_connections c ON c.id=si.source_connection_id
 LEFT JOIN content_objects co ON co.id=p.content_object_id
 LEFT JOIN LATERAL(SELECT j.type,j.state,j.attempt,j.available_at,j.updated_at FROM jobs j WHERE
 (j.payload->>'publication_id'=p.id OR (j.type='artifact.fetch' AND j.payload->>'version_id'=p.source_item_version_id))
 AND j.type IN ('artifact.fetch','test.upload','test.poll','test.remove')
 ORDER BY CASE WHEN j.state IN ('pending','running','retry') THEN 0 ELSE 1 END,j.updated_at DESC,j.id DESC LIMIT 1) j ON TRUE
 LEFT JOIN LATERAL(SELECT f.id,f.job_type,f.error_code,f.last_error,f.created_at FROM job_failures f LEFT JOIN jobs fj ON fj.id=f.job_id WHERE f.state='open' AND (f.publication_id=p.id OR (f.job_type='artifact.fetch' AND COALESCE(NULLIF(f.business_version_id,''),fj.payload->>'version_id')=p.source_item_version_id)) ORDER BY f.created_at DESC,f.id DESC LIMIT 1) f ON TRUE
), classified AS (
 SELECT *,
 CASE WHEN action='remove' AND retrieval_state='disabled' THEN 'completed'
 WHEN action<>'remove' AND processing_state='completed' THEN 'completed'
 WHEN job_state IN ('pending','retry') AND job_attempt>0 THEN 'retrying'
 WHEN job_state='running' THEN 'running'
 WHEN job_state IN ('pending','retry') THEN 'waiting'
 WHEN job_state='failed' OR failure_id<>'' OR processing_state IN ('failed','stalled') OR ingest_state='failed' OR retrieval_state='failed' THEN 'attention'
 WHEN processing_state='cancelled' THEN 'cancelled'
 WHEN action='remove' THEN 'waiting'
 WHEN processing_state IN ('processing','finalizing') THEN 'running'
 ELSE 'waiting' END AS status,
 CASE WHEN action='remove' AND retrieval_state='disabled' THEN 'finished'
 WHEN action='remove' THEN 'removal'
 WHEN processing_state IN ('completed','cancelled') THEN 'finished'
 WHEN job_type='artifact.fetch' AND job_state IN ('pending','running','retry') THEN 'fetch'
 WHEN processing_state='finalizing' THEN 'indexing'
 WHEN processing_state='processing' OR job_type='test.poll' THEN 'parsing'
 WHEN ingest_state='uploading' OR job_type='test.upload' THEN 'upload'
 WHEN failure_type='artifact.fetch' OR COALESCE(content_state,'')<>'verified' THEN 'fetch'
 ELSE 'waiting' END AS stage
 FROM base
), projected AS (
 SELECT id,title,path,source_id,source_name,target_scope,target_kb,version_id,retry_count,updated_at,action,stage,status,failure_id,
 CASE WHEN status<>'attention' THEN ''
 WHEN action='remove' THEN CASE WHEN job_type='test.remove' AND job_state='failed' AND retrieval_state IN ('failed','disabling') AND policy_state='blocked' THEN 'remove' ELSE '' END
 WHEN failure_type='artifact.fetch' THEN 'fetch'
 WHEN content_state='verified' AND local_spool_ref<>'' AND processing_state IN ('failed','stalled','pending') THEN 'upload' ELSE '' END AS retry_kind,
 CASE WHEN status='completed' THEN CASE WHEN action='remove' THEN '已从测试库移除；来源文件保留' ELSE '测试库处理完成；未代表已发布生产' END
 WHEN status='cancelled' THEN '处理已取消，记录保留'
 WHEN status='retrying' THEN '等待自动重试；下次调度 ' || COALESCE(to_char(available_at AT TIME ZONE 'Asia/Shanghai','YYYY-MM-DD HH24:MI:SS'),'未提供')
 WHEN status='attention' THEN COALESCE(NULLIF(last_error,''),NULLIF(failure_error,''),'处理异常，请查看详情')
 WHEN stage='removal' THEN CASE WHEN status='running' THEN '正在移除测试库知识' ELSE '等待测试库移除任务' END
 WHEN stage='fetch' THEN '等待或正在获取源文件'
 WHEN stage='waiting' THEN '文件已就绪，等待后台处理调度'
 WHEN stage='upload' THEN '等待或正在上传测试知识库'
 WHEN stage='indexing' THEN '正在索引与增强'
 ELSE '正在解析处理' END AS detail
 FROM classified
), filtered AS (
 SELECT * FROM projected WHERE ($1='' OR strpos(lower(title || ' ' || path),lower($1))>0)
 AND ($2='' OR source_id=$2) AND ($3='' OR target_scope=$3) AND ($4='' OR action=$4)
 AND ($5='' OR ($5='active' AND status NOT IN ('completed','cancelled')) OR status=$5)
 AND ($6='' OR stage=$6) AND ($7='' OR id=$7) AND ($10='' OR target_kb=$10)
 AND ($11='' OR updated_at>=NULLIF($11,'')::timestamptz) AND ($12='' OR updated_at<=NULLIF($12,'')::timestamptz)
) `

func (s *Store) ListMonitorTasks(ctx context.Context, f MonitorTaskFilter) (MonitorTaskPage, error) {
	if f.Limit < 1 || f.Limit > 100 || f.Offset < 0 {
		return MonitorTaskPage{}, errors.New("invalid monitor pagination")
	}
	var raw []byte
	err := s.db.QueryRow(ctx, monitorTasksCTE+`SELECT jsonb_build_object('items',COALESCE((SELECT jsonb_agg(to_jsonb(x)||jsonb_build_object('history',COALESCE((SELECT jsonb_agg(e ORDER BY e.at DESC,e.kind,e.detail) FROM (SELECT * FROM history_events ORDER BY at DESC,kind,detail LIMIT 50)e),'[]'::jsonb)) ORDER BY x.updated_at DESC,x.id) FROM (SELECT * FROM filtered ORDER BY updated_at DESC,id LIMIT $8 OFFSET $9)x),'[]'::jsonb),'total',(SELECT count(*) FROM filtered),'limit',$8::int,'offset',$9::int,'retryable',(SELECT count(*) FROM filtered WHERE retry_kind<>''),'sources',COALESCE((SELECT jsonb_agg(x ORDER BY x.name) FROM (SELECT DISTINCT source_id AS id,source_name AS name FROM projected)x),'[]'::jsonb),'targets',COALESCE((SELECT jsonb_agg(x ORDER BY x.name) FROM (SELECT DISTINCT target_kb AS id,target_kb AS name FROM projected)x),'[]'::jsonb))`, f.Search, f.Source, f.Scope, f.Action, f.Status, f.Stage, f.ID, f.Limit, f.Offset, f.Target, f.Since, f.Until).Scan(&raw)
	if err != nil {
		return MonitorTaskPage{}, err
	}
	var result MonitorTaskPage
	err = json.Unmarshal(raw, &result)
	return result, err
}