package piplan

import (
	"context"
	"encoding/json"
	"fmt"
	"strings"

	"laodingbot/internal/logger"
)

// Feature 产品经理视角输出的业务特性。
type Feature struct {
	FeatureID          string   `json:"feature_id"`
	Title              string   `json:"title"`
	BenefitHypothesis  string   `json:"benefit_hypothesis"`
	AcceptanceCriteria []string `json:"acceptance_criteria"`
}

// Enabler 系统架构师视角输出的技术赋能特性（架构跑道）。
type Enabler struct {
	EnablerID            string `json:"enabler_id"`
	Title                string `json:"title"`
	ArchitecturalPurpose string `json:"architectural_purpose"`
}

// NFRs 非功能性需求。
type NFRs struct {
	Performance string `json:"performance"`
	Security    string `json:"security"`
}

// Dependency RTE 梳理的任务依赖关系。
type Dependency struct {
	SourceID string `json:"source_id"`
	TargetID string `json:"target_id"`
	Reason   string `json:"reason"`
}

// PIPlanInput publish_pi_plan 工具的完整输入结构。
type PIPlanInput struct {
	PIVision     string       `json:"pi_vision"`
	Features     []Feature    `json:"features"`
	Enablers     []Enabler    `json:"enablers"`
	NFRs         NFRs         `json:"nfrs"`
	Dependencies []Dependency `json:"dependencies"`
}

// Tool 实现 SAFe PI 规划发布工具。
type Tool struct {
	maxOutputChars int
	log            *logger.Logger
}

// New 创建一个新的 publish_pi_plan 工具实例。
func New(maxOutputChars int, log *logger.Logger) *Tool {
	if maxOutputChars <= 0 {
		maxOutputChars = 20000
	}
	return &Tool{
		maxOutputChars: maxOutputChars,
		log:            log,
	}
}

func (t *Tool) Name() string { return "publish_pi_plan" }

func (t *Tool) Description() string {
	return `当铁三角（PM, 架构师, RTE）完成 PI 规划推演后，调用此工具输出标准化的架构蓝图与任务清单。输入为 JSON，包含 pi_vision, features, enablers, nfrs, dependencies 字段。`
}

func (t *Tool) Call(ctx context.Context, input string) (string, error) {
	plan, err := parseInput(input)
	if err != nil {
		return "", fmt.Errorf("publish_pi_plan: invalid input: %w", err)
	}

	if err := validate(plan); err != nil {
		return "", fmt.Errorf("publish_pi_plan: validation failed: %w", err)
	}

	if t.log != nil {
		t.log.Infof("publish_pi_plan: features=%d enablers=%d deps=%d",
			len(plan.Features), len(plan.Enablers), len(plan.Dependencies))
	}

	output := render(plan)

	if len([]rune(output)) > t.maxOutputChars {
		output = string([]rune(output)[:t.maxOutputChars])
	}
	return output, nil
}

func parseInput(input string) (*PIPlanInput, error) {
	raw := strings.TrimSpace(input)
	if raw == "" {
		return nil, fmt.Errorf("empty input")
	}

	var plan PIPlanInput
	if err := json.Unmarshal([]byte(raw), &plan); err != nil {
		return nil, fmt.Errorf("JSON parse error: %w", err)
	}
	return &plan, nil
}

func validate(p *PIPlanInput) error {
	if strings.TrimSpace(p.PIVision) == "" {
		return fmt.Errorf("pi_vision is required")
	}
	if len(p.Features) == 0 {
		return fmt.Errorf("at least one feature is required")
	}
	for i, f := range p.Features {
		if strings.TrimSpace(f.FeatureID) == "" {
			return fmt.Errorf("features[%d].feature_id is required", i)
		}
		if strings.TrimSpace(f.Title) == "" {
			return fmt.Errorf("features[%d].title is required", i)
		}
		if strings.TrimSpace(f.BenefitHypothesis) == "" {
			return fmt.Errorf("features[%d].benefit_hypothesis is required", i)
		}
		if len(f.AcceptanceCriteria) == 0 {
			return fmt.Errorf("features[%d].acceptance_criteria requires at least one item", i)
		}
	}
	for i, e := range p.Enablers {
		if strings.TrimSpace(e.EnablerID) == "" {
			return fmt.Errorf("enablers[%d].enabler_id is required", i)
		}
		if strings.TrimSpace(e.Title) == "" {
			return fmt.Errorf("enablers[%d].title is required", i)
		}
		if strings.TrimSpace(e.ArchitecturalPurpose) == "" {
			return fmt.Errorf("enablers[%d].architectural_purpose is required", i)
		}
	}
	if strings.TrimSpace(p.NFRs.Performance) == "" {
		return fmt.Errorf("nfrs.performance is required")
	}
	if strings.TrimSpace(p.NFRs.Security) == "" {
		return fmt.Errorf("nfrs.security is required")
	}
	for i, d := range p.Dependencies {
		if strings.TrimSpace(d.SourceID) == "" {
			return fmt.Errorf("dependencies[%d].source_id is required", i)
		}
		if strings.TrimSpace(d.TargetID) == "" {
			return fmt.Errorf("dependencies[%d].target_id is required", i)
		}
	}
	return nil
}

// render 将 PI 规划输入渲染为标准化的 Markdown 架构蓝图与任务清单。
func render(p *PIPlanInput) string {
	var b strings.Builder

	// ── 标题 ──
	b.WriteString("# PI 规划架构蓝图与任务清单\n\n")

	// ── 1. PI 愿景 ──
	b.WriteString("## 1. PI 愿景\n\n")
	b.WriteString(strings.TrimSpace(p.PIVision))
	b.WriteString("\n\n")

	// ── 2. 业务特性清单 (Features) ──
	b.WriteString("## 2. 业务特性清单 (Features)\n\n")
	for _, f := range p.Features {
		b.WriteString(fmt.Sprintf("### %s — %s\n\n", f.FeatureID, f.Title))
		b.WriteString(fmt.Sprintf("**业务价值假设**: %s\n\n", f.BenefitHypothesis))
		b.WriteString("**验收标准 (AC)**:\n\n")
		for j, ac := range f.AcceptanceCriteria {
			b.WriteString(fmt.Sprintf("- [ ] AC-%d: %s\n", j+1, ac))
		}
		b.WriteString("\n")
	}

	// ── 3. 技术赋能特性 (Enablers / 架构跑道) ──
	b.WriteString("## 3. 技术赋能特性 (Enablers / 架构跑道)\n\n")
	if len(p.Enablers) == 0 {
		b.WriteString("_无技术赋能特性。_\n\n")
	} else {
		b.WriteString("| Enabler ID | 名称 | 架构意图 |\n")
		b.WriteString("|------------|------|----------|\n")
		for _, e := range p.Enablers {
			b.WriteString(fmt.Sprintf("| %s | %s | %s |\n",
				e.EnablerID, e.Title, e.ArchitecturalPurpose))
		}
		b.WriteString("\n")
	}

	// ── 4. 非功能性需求 (NFRs) ──
	b.WriteString("## 4. 非功能性需求 (NFRs)\n\n")
	b.WriteString(fmt.Sprintf("- **性能**: %s\n", p.NFRs.Performance))
	b.WriteString(fmt.Sprintf("- **安全与合规**: %s\n", p.NFRs.Security))
	b.WriteString("\n")

	// ── 5. 依赖关系图 ──
	b.WriteString("## 5. 依赖关系\n\n")
	if len(p.Dependencies) == 0 {
		b.WriteString("_无跨任务依赖。_\n\n")
	} else {
		b.WriteString("| 前置任务 (Source) | 后续任务 (Target) | 依赖原因 |\n")
		b.WriteString("|-------------------|-------------------|----------|\n")
		for _, d := range p.Dependencies {
			reason := d.Reason
			if reason == "" {
				reason = "—"
			}
			b.WriteString(fmt.Sprintf("| %s | %s | %s |\n",
				d.SourceID, d.TargetID, reason))
		}
		b.WriteString("\n")
	}

	// ── 6. 建议执行顺序 ──
	b.WriteString("## 6. 建议执行顺序\n\n")
	order := computeExecutionOrder(p)
	for i, id := range order {
		b.WriteString(fmt.Sprintf("%d. %s\n", i+1, id))
	}
	b.WriteString("\n")

	// ── 7. 质量门禁检查清单 ──
	b.WriteString("## 7. 质量门禁检查清单\n\n")
	b.WriteString("### 业务验收测试用例\n\n")
	for _, f := range p.Features {
		for j, ac := range f.AcceptanceCriteria {
			b.WriteString(fmt.Sprintf("- [ ] [%s] AC-%d: %s\n", f.FeatureID, j+1, ac))
		}
	}
	b.WriteString("\n### 非功能性验证\n\n")
	b.WriteString(fmt.Sprintf("- [ ] 性能压测: %s\n", p.NFRs.Performance))
	b.WriteString(fmt.Sprintf("- [ ] 安全扫描: %s\n", p.NFRs.Security))
	b.WriteString("\n")

	return b.String()
}

// computeExecutionOrder 根据依赖关系计算拓扑排序的执行顺序。
// 先排 Enabler，再排 Feature；无依赖的排在前面。
func computeExecutionOrder(p *PIPlanInput) []string {
	// 收集所有 ID
	allIDs := make([]string, 0, len(p.Enablers)+len(p.Features))
	idSet := make(map[string]bool)
	for _, e := range p.Enablers {
		allIDs = append(allIDs, e.EnablerID)
		idSet[e.EnablerID] = true
	}
	for _, f := range p.Features {
		allIDs = append(allIDs, f.FeatureID)
		idSet[f.FeatureID] = true
	}

	// 构建入度表和邻接表
	inDegree := make(map[string]int)
	adj := make(map[string][]string)
	for _, id := range allIDs {
		inDegree[id] = 0
	}
	for _, d := range p.Dependencies {
		if !idSet[d.SourceID] || !idSet[d.TargetID] {
			continue
		}
		adj[d.SourceID] = append(adj[d.SourceID], d.TargetID)
		inDegree[d.TargetID]++
	}

	// Kahn 拓扑排序
	queue := make([]string, 0)
	// 先加入度为 0 的 Enabler，再加入度为 0 的 Feature，保持稳定顺序
	for _, e := range p.Enablers {
		if inDegree[e.EnablerID] == 0 {
			queue = append(queue, e.EnablerID)
		}
	}
	for _, f := range p.Features {
		if inDegree[f.FeatureID] == 0 {
			queue = append(queue, f.FeatureID)
		}
	}

	var result []string
	for len(queue) > 0 {
		curr := queue[0]
		queue = queue[1:]
		result = append(result, curr)
		for _, next := range adj[curr] {
			inDegree[next]--
			if inDegree[next] == 0 {
				queue = append(queue, next)
			}
		}
	}

	// 如果存在环，将未排序的节点追加到末尾并标记
	if len(result) < len(allIDs) {
		for _, id := range allIDs {
			if inDegree[id] > 0 {
				result = append(result, id+" ⚠️(循环依赖)")
			}
		}
	}

	return result
}