package controller

import (
	"crypto/sha256"
	"encoding/hex"
	"sort"
	"strconv"
	"strings"

	"github.com/gin-gonic/gin"

	"github.com/heicode/manager/common"
	"github.com/heicode/manager/model"
)

// Preflight / execution-summary (#29 EPIC, sub-issues #39 缺失项检测 + #40 可读执行摘要).
//
// Manager 是辅助控制台,不是编码入口:用户在启动 agent 前应看到一份「执行摘要」——
// 这个 agent 会用哪些资源、还缺什么、有哪些高危操作、预算上限是多少 —— 只确认摘要而非
// 面对完整参数(产品文档「准备清单 / 推荐摘要」第四、五步)。
//
// 本文件实现只读的 preflight:GET /api/heicode/preflight?template_id=&binding_ids=1,2,3
// 返回缺失项 + 可读摘要。#41(confirm + 审计 + 防篡改版本校验)在此之上单独实现。
//
// 红线(#40):resource 视图绝不暴露 secret_ref / channelId / base_url / price 等敏感字段;
// 高危操作用固定 enum,不自由文本。

// 高危操作固定 enum(#40 红线):只能取以下值。
const (
	highRiskProductionDeploy = "production_deploy"      // 生产部署 / 代码改动推送
	highRiskDBWrite          = "db_write"               // 数据库写入
	highRiskCloudDelete      = "cloud_resource_delete"  // 云资源删除
	highRiskProductionSecret = "production_secret"      // 生产密钥访问
	highRiskLargeBudget      = "large_budget"           // 大额预算消耗
)

var highRiskOpLabels = map[string]string{
	highRiskProductionDeploy: "生产部署 / 代码改动",
	highRiskDBWrite:          "数据库写入",
	highRiskCloudDelete:      "云资源删除",
	highRiskProductionSecret: "生产密钥访问",
	highRiskLargeBudget:      "大额预算消耗",
}

// 准备清单要求用户连接的资源类别(#39 缺失项检测)。budget 单独判定。
var preflightRequiredKinds = []struct {
	kind  string // 与 ResourceBinding.ResourceType 对齐
	label string
}{
	{"git", "代码仓库(Git)"},
	{"sk", "SK 资源包"},
	{"project_document", "项目文档"},
	{"cloud_account", "云账号"},
}

type preflightRole struct {
	TemplateID string `json:"template_id"`
	Name       string `json:"name"`
	Model      string `json:"model"`
}

// preflightResource 是资源的**脱敏**视图:绝不含 secret_ref/channelId/base_url/price。
type preflightResource struct {
	BindingID int    `json:"binding_id"`
	Type      string `json:"type"`
	Provider  string `json:"provider"`
	Name      string `json:"name"`
	Status    string `json:"status"`
	HasSecret bool   `json:"has_secret"` // 是否已绑定凭证(布尔,不含凭证本身)
}

type preflightMissing struct {
	Kind   string `json:"kind"`
	Reason string `json:"reason"`
}

type preflightHighRisk struct {
	Op               string `json:"op"`    // 固定 enum
	Label            string `json:"label"` // 中文展示
	RequiresApproval bool   `json:"requires_approval"`
}

type preflightBudget struct {
	RemainingQuota int64   `json:"remaining_quota"`
	QuotaPerUnit   float64 `json:"quota_per_unit"`
	TierMaxAgents  int     `json:"tier_max_agents"`
	CurrentAgents  int     `json:"current_agents"`
}

type preflightSummary struct {
	TemplateID     string              `json:"template_id"`
	AgentRole      preflightRole       `json:"agent_role"`
	Resources      []preflightResource `json:"resources"`
	InvalidBindings []int              `json:"invalid_bindings"` // 请求里无效/非本人/非 active 的绑定 id
	Missing        []preflightMissing  `json:"missing"`
	HighRiskOps    []preflightHighRisk `json:"high_risk_ops"`
	Budget         preflightBudget     `json:"budget"`
	ApprovalPolicy gin.H               `json:"approval_policy"`
	Ready          bool                `json:"ready"`             // 缺失项为空 + agent 配额未满
	Version        string              `json:"version,omitempty"` // 防篡改摘要版本(#41);由稳定子集派生

	// tplDigest 是模板**安全面**(definition + model + name)的摘要,纳入版本哈希,使管理员
	// 修改同一 template_key 的 definition/model 后旧确认失效(#41 复审 #3)。不序列化。
	tplDigest string
}

// confirmBindingIDs 返回摘要里有效(已解析)资源的绑定 id,用于审计记录。
func (s preflightSummary) confirmBindingIDs() []int {
	ids := make([]int, 0, len(s.Resources))
	for _, r := range s.Resources {
		ids = append(ids, r.BindingID)
	}
	return ids
}

// computePreflightVersion 在摘要的**安全相关且稳定**子集上派生版本哈希(#41):
// template_id + 资源(binding_id/type/provider/name/status/has_secret)+ 高危操作 +
// 必需资源类缺失项。**刻意排除**易变的预算数字(remaining_quota 随每次调用变化)与
// budget/agent_slot 缺失项,否则版本会无意义地频繁变化导致部署总被拒。资源(增删/改类型/
// 改 secret)或高危面变化 → 哈希变化 → 部署校验拒绝(防篡改 / 防漂移)。
func computePreflightVersion(s preflightSummary) string {
	parts := make([]string, 0, len(s.Resources)+len(s.HighRiskOps)+len(s.Missing)+2)
	parts = append(parts, "tpl="+s.TemplateID)
	parts = append(parts, "tpld="+s.tplDigest) // 模板安全面摘要(#41 复审 #3:模板变更翻转版本)

	res := make([]string, 0, len(s.Resources))
	for _, r := range s.Resources {
		res = append(res, strconv.Itoa(r.BindingID)+":"+r.Type+":"+r.Provider+":"+r.Name+":"+r.Status+":"+boolStr(r.HasSecret))
	}
	sort.Strings(res)
	parts = append(parts, "res=["+strings.Join(res, ",")+"]")

	ops := make([]string, 0, len(s.HighRiskOps))
	for _, h := range s.HighRiskOps {
		ops = append(ops, h.Op)
	}
	sort.Strings(ops)
	parts = append(parts, "risk=["+strings.Join(ops, ",")+"]")

	// 仅纳入「必需资源类」缺失(git/sk/project_document/cloud_account),排除 budget/agent_slot。
	miss := make([]string, 0)
	for _, m := range s.Missing {
		if m.Kind != "budget" && m.Kind != "agent_slot" {
			miss = append(miss, m.Kind)
		}
	}
	sort.Strings(miss)
	parts = append(parts, "missing=["+strings.Join(miss, ",")+"]")

	sum := sha256.Sum256([]byte(strings.Join(parts, "|")))
	return "pfv1_" + hex.EncodeToString(sum[:])[:32]
}

func boolStr(b bool) string {
	if b {
		return "1"
	}
	return "0"
}

// withPreflightVersion 在摘要上填入版本哈希后返回(GET / confirm 都用)。
func withPreflightVersion(s preflightSummary) preflightSummary {
	s.Version = computePreflightVersion(s)
	return s
}

// verifyDeployPreflight 在部署时执行 #41 的防篡改确认校验。返回 (allowed, message):
//   - HEICODE_PREFLIGHT_REQUIRED=true:必须带匹配的 preflight_version;
//   - 否则:若客户端带了 preflight_version 则必须与实时状态匹配(漂移/篡改防护);未带则放行(向后兼容)。
//
// "匹配" = 用**当前**(模板、绑定、安全面)重算的版本等于传入版本。确认后任何对已绑资源/模板/
// 高危面的改动都会翻转哈希并拒绝部署。
func verifyDeployPreflight(userID int, templateID string, bindingIDs []int, providedVersion string) (bool, string) {
	required := common.GetEnvOrDefaultBool("HEICODE_PREFLIGHT_REQUIRED", false)
	providedVersion = strings.TrimSpace(providedVersion)
	if providedVersion == "" {
		if required {
			return false, "preflight confirmation required: call POST /api/heicode/preflight/confirm and pass its version as preflight_version"
		}
		return true, "" // 向后兼容:未带 version 且非强制 → 放行
	}
	summary, ok := buildPreflightSummary(userID, templateID, normalizeBindingIDs(bindingIDs))
	if !ok {
		return false, "unknown template_id"
	}
	// (a) 漂移/篡改防护:当前重算版本必须与传入一致(资源/模板安全面变化即翻转,#41 复审 #3)。
	if computePreflightVersion(summary) != providedVersion {
		return false, "preflight changed since confirmation (resources/template drifted or tampered); re-run preflight confirm and retry"
	}
	// (b) 当前仍须 Ready(#41 复审 #2):预算/agent_slot 等易变项不进版本哈希,故部署时重新校验,
	// 防止用 confirm 时的 ready 版本在余额耗尽/槽位占满后仍能启动。
	if !summary.Ready {
		return false, "preflight no longer ready (e.g. budget/agent slot); re-run preflight and resolve missing items"
	}
	// (c) 必须存在一条该版本的已确认记录(#41 复审 #1/#4):杜绝直接拿 GET version 绕过 confirm。
	exists, err := model.PreflightConfirmationExists(userID, templateID, providedVersion, common.GetTimestamp()*1000)
	if err != nil {
		return false, "failed to verify preflight confirmation"
	}
	if !exists {
		return false, "this preflight version was never confirmed (or has expired); call POST /api/heicode/preflight/confirm first"
	}
	return true, ""
}

// normalizeBindingIDs 去重 + 去非正数,保持顺序(用于 confirm/deploy 的 []int 入参)。
func normalizeBindingIDs(in []int) []int {
	out := make([]int, 0, len(in))
	seen := map[int]bool{}
	for _, n := range in {
		if n > 0 && !seen[n] {
			seen[n] = true
			out = append(out, n)
		}
	}
	return out
}

// computePreflight 是纯函数(无 DB / 无 gin.Context),便于单测。给定模板、已解析的脱敏
// 资源视图、用户剩余额度、tier 上限与当前在跑 agent 数,产出执行摘要。
func computePreflight(tpl model.AgentTemplate, resources []preflightResource, invalidBindings []int,
	remainingQuota int64, quotaPerUnit float64, maxAgents, currentAgents int) preflightSummary {

	present := map[string]bool{}
	for _, r := range resources {
		present[r.Type] = true
	}

	// #39 缺失项:必需资源类别未绑定 + 预算不足。
	missing := make([]preflightMissing, 0)
	for _, req := range preflightRequiredKinds {
		if !present[req.kind] {
			missing = append(missing, preflightMissing{Kind: req.kind, Reason: "未绑定" + req.label})
		}
	}
	budgetInsufficient := remainingQuota <= 0
	if budgetInsufficient {
		missing = append(missing, preflightMissing{Kind: "budget", Reason: "账户可用额度不足,请充值或开通订阅"})
	}
	agentSlotFull := maxAgents > 0 && currentAgents >= maxAgents
	if agentSlotFull {
		missing = append(missing, preflightMissing{Kind: "agent_slot", Reason: "在跑 Agent 数已达上限(" + strconv.Itoa(maxAgents) + "),请先停止/删除一个"})
	}

	// #40 高危操作(固定 enum):由已绑资源类型推导,均需审批。
	highRisk := make([]preflightHighRisk, 0)
	addRisk := func(op string) {
		highRisk = append(highRisk, preflightHighRisk{Op: op, Label: highRiskOpLabels[op], RequiresApproval: true})
	}
	if present["git"] {
		addRisk(highRiskProductionDeploy)
	}
	if present["database"] {
		addRisk(highRiskDBWrite)
	}
	if present["cloud_account"] || present["cloud_resource"] {
		addRisk(highRiskCloudDelete)
		addRisk(highRiskProductionSecret)
	}
	// 预算是标准确认项:启动前用户须确认本任务的预算口径。
	addRisk(highRiskLargeBudget)

	return preflightSummary{
		TemplateID: tpl.TemplateKey,
		AgentRole: preflightRole{
			TemplateID: tpl.TemplateKey,
			Name:       tpl.NameZh,
			Model:      tpl.Model,
		},
		Resources:       resources,
		InvalidBindings: invalidBindings,
		Missing:         missing,
		HighRiskOps:     highRisk,
		Budget: preflightBudget{
			RemainingQuota: remainingQuota,
			QuotaPerUnit:   quotaPerUnit,
			TierMaxAgents:  maxAgents,
			CurrentAgents:  currentAgents,
		},
		ApprovalPolicy: gin.H{"mode": "per_high_risk_op"},
		Ready:          len(missing) == 0,
		tplDigest:      templateSecurityDigest(tpl),
	}
}

// templateSecurityDigest 取模板安全面(definition + model + name)的短摘要,纳入版本哈希。
func templateSecurityDigest(tpl model.AgentTemplate) string {
	sum := sha256.Sum256([]byte(tpl.Definition + "|" + tpl.Model + "|" + tpl.NameZh))
	return hex.EncodeToString(sum[:])[:16]
}

// parsePreflightBindingIDs 解析 binding_ids 查询参数(支持逗号分隔 "1,2,3" 或重复 key)。
func parsePreflightBindingIDs(c *gin.Context) []int {
	raw := c.QueryArray("binding_ids")
	if len(raw) == 1 && strings.Contains(raw[0], ",") {
		raw = strings.Split(raw[0], ",")
	}
	ids := make([]int, 0, len(raw))
	seen := map[int]bool{}
	for _, s := range raw {
		if n, err := strconv.Atoi(strings.TrimSpace(s)); err == nil && n > 0 && !seen[n] {
			seen[n] = true
			ids = append(ids, n)
		}
	}
	return ids
}

// buildPreflightSummary loads the template + resolved (redacted) resource views +
// quota/tier/current-agent state for (userID, templateID, bindingIDs) and computes
// the execution summary. Returns (summary, ok); ok=false means unknown template.
// Shared by the GET preflight, POST confirm, and the deploy-time version check.
func buildPreflightSummary(userID int, templateID string, bindingIDs []int) (preflightSummary, bool) {
	tpl, ok := loadAgentTemplate(templateID)
	if !ok {
		return preflightSummary{}, false
	}
	resources := make([]preflightResource, 0, len(bindingIDs))
	invalid := make([]int, 0)
	for _, id := range bindingIDs {
		var b model.ResourceBinding
		if err := model.DB.Where("id = ? AND user_id = ? AND status = ?", id, userID, "active").First(&b).Error; err != nil {
			invalid = append(invalid, id)
			continue
		}
		resources = append(resources, preflightResource{
			BindingID: b.Id,
			Type:      b.ResourceType,
			Provider:  b.Provider,
			Name:      b.Name,
			Status:    b.Status,
			HasSecret: strings.TrimSpace(b.SecretRef) != "",
		})
	}
	var remainingQuota int64
	if u, err := model.GetUserById(userID, false); err == nil && u != nil {
		remainingQuota = int64(u.Quota)
	}
	maxAgents := model.GetUserMaxAgents(userID, common.GetEnvOrDefault("HEICODE_MAX_AGENTS_PER_USER", 5))
	var currentAgents int64
	_ = model.DB.Model(&model.AgentDeployment{}).
		Where("user_id = ? AND template_id <> '' AND LOWER(status) <> ?", strconv.Itoa(userID), "stopped").
		Count(&currentAgents).Error
	return computePreflight(tpl, resources, invalid, remainingQuota, common.QuotaPerUnit, maxAgents, int(currentAgents)), true
}

// HeicodePreflight: GET /api/heicode/preflight?template_id=&binding_ids=1,2,3 (#39 + #40).
func HeicodePreflight(c *gin.Context) {
	userID := c.GetInt("id")
	if userID <= 0 {
		agentError(c, "POLICY_REJECTED", "authentication required")
		return
	}
	if model.DB == nil {
		agentError(c, "DEPLOYMENT_PERSIST_FAILED", "database not initialised")
		return
	}
	templateID := strings.TrimSpace(c.Query("template_id"))
	if templateID == "" {
		agentError(c, "POLICY_REJECTED", "template_id is required")
		return
	}
	summary, ok := buildPreflightSummary(userID, templateID, parsePreflightBindingIDs(c))
	if !ok {
		agentError(c, "POLICY_REJECTED", "unknown template_id")
		return
	}
	common.ApiSuccess(c, withPreflightVersion(summary))
}

// HeicodePreflightConfirm: POST /api/heicode/preflight/confirm (#41).
// Body: {template_id, binding_ids:[...]}. Recomputes the summary, derives a
// tamper-proof version hash over the security-relevant (non-volatile) content,
// and records an audit event (who / when / which version). The client passes the
// returned `version` to POST /api/heicode/agents; deploy re-derives the version
// from the live state and rejects if it changed (resource/template tampered or
// drifted since confirmation).
func HeicodePreflightConfirm(c *gin.Context) {
	userID := c.GetInt("id")
	if userID <= 0 {
		agentError(c, "POLICY_REJECTED", "authentication required")
		return
	}
	if model.DB == nil {
		agentError(c, "DEPLOYMENT_PERSIST_FAILED", "database not initialised")
		return
	}
	var req struct {
		TemplateID string `json:"template_id"`
		BindingIDs []int  `json:"binding_ids"`
	}
	if err := common.UnmarshalBodyReusable(c, &req); err != nil {
		agentError(c, "POLICY_REJECTED", "invalid request body")
		return
	}
	req.TemplateID = strings.TrimSpace(req.TemplateID)
	if req.TemplateID == "" {
		agentError(c, "POLICY_REJECTED", "template_id is required")
		return
	}
	summary, ok := buildPreflightSummary(userID, req.TemplateID, normalizeBindingIDs(req.BindingIDs))
	if !ok {
		agentError(c, "POLICY_REJECTED", "unknown template_id")
		return
	}
	if !summary.Ready {
		agentError(c, "POLICY_REJECTED", "preflight not ready: resolve missing items before confirming")
		return
	}
	version := computePreflightVersion(summary)
	bindingKey := model.PreflightBindingKey(req.BindingIDs)

	// 强一致的确认记录(#41 复审 #1/#4):部署侧据此校验「该版本曾被 confirm」。**先持久化成功**
	// 才算确认;写失败直接报错(不像审计那样 best-effort),否则部署侧会因查不到记录而拒绝。
	nowMs := common.GetTimestamp() * 1000
	ttlSec := common.GetEnvOrDefault("HEICODE_PREFLIGHT_CONFIRMATION_TTL_SECONDS", 3600)
	expiresAtMs := int64(0)
	if ttlSec > 0 {
		expiresAtMs = nowMs + int64(ttlSec)*1000
	}
	if err := model.InsertPreflightConfirmation(&model.PreflightConfirmation{
		UserID:      userID,
		TemplateID:  req.TemplateID,
		BindingKey:  bindingKey,
		Version:     version,
		CreatedAtMs: nowMs,
		ExpiresAtMs: expiresAtMs,
	}); err != nil {
		common.SysLog("preflight confirm persist failed: " + err.Error())
		agentError(c, "DEPLOYMENT_PERSIST_FAILED", "failed to persist preflight confirmation")
		return
	}

	// 附加审计流:谁、何时、确认了哪个版本(best-effort,与上面的强一致记录互补)。
	detail, _ := common.Marshal(gin.H{
		"version":     version,
		"template_id": req.TemplateID,
		"binding_key": bindingKey,
	})
	model.InsertAgentAuditEvent(&model.AgentAuditEvent{
		Event:       "preflight.confirmed",
		Actor:       strconv.Itoa(userID),
		UserID:      strconv.Itoa(userID),
		Resource:    "template:" + req.TemplateID,
		Result:      "ok",
		DetailsJSON: string(detail),
	})

	common.ApiSuccess(c, gin.H{
		"version":     version,
		"template_id": req.TemplateID,
		"summary":     withPreflightVersion(summary),
		"confirmed":   true,
	})
}