import { BaseAgent, AgentContext, AgentResult } from "./base.js";
import { CIAgentFiles, RequirementsMd, RoadmapMd, ArchitectureMd } from "../core/ciagent-files.js";
import { GitContext } from "../core/git-context.js";
import { CommitBuilder } from "../core/commit-builder.js";
import { writeFile, readFile, ensureDir } from "../utils/file.js";
import { execSync } from "node:child_process";
import * as path from "node:path";

export interface PlannerResult {
  success: boolean;
  planCount: number;
  waves: { wave: number; plans: string[] }[];
  decisions: number;
  error?: string;
}

interface PlanEntry {
  name: string;
  wave: number;
  requirements: string[];
  dependsOn: string[];
  tasks: string[];
  mustHaves: string[];
}

export class PlannerAgent extends BaseAgent {
  readonly name = "planner";
  readonly description = "Creates phase plans with tasks. Never sets autonomous:false — decomposes into verifiable subtasks.";
  readonly workflow = "plan";

  async execute(context: AgentContext): Promise<AgentResult> {
    const start = Date.now();
    this.log("Creating phase plan...");

    if (context.backend) {
      const taskPrompt = await this.buildBackendTaskPrompt(context);
      const result = await this.executeViaBackend(context, taskPrompt);
      return { ...result, duration_ms: Date.now() - start };
    }

    return this.executeMechanical(context, start);
  }

  private async buildBackendTaskPrompt(context: AgentContext): Promise<string> {
    const ciFiles = new CIAgentFiles(context.project_path);
    const parts: string[] = [
      `Create a phase plan for stage ${context.stage}, phase ${context.phase}.`,
      "",
      "## Project Context",
    ];

    const roadmap = ciFiles.readRoadmapMd();
    if (roadmap) {
      const currentPhase = roadmap.phases.find((p) => p.number === context.phase);
      if (currentPhase) {
        parts.push("", "### Phase Goal", currentPhase.description);
        parts.push("", "### Phase Requirements", currentPhase.requirements.join(", ") || "None specified");
        parts.push("", "### Phase Dependencies", currentPhase.dependsOn.length > 0 ? currentPhase.dependsOn.map((d) => `Phase ${d}`).join(", ") : "None");
        parts.push("", "### Success Criteria", ...currentPhase.successCriteria.map((sc) => `- ${sc}`));
      }
    }

    const requirements = ciFiles.readRequirementsMd();
    if (requirements) {
      const phaseReqs = requirements.traceability.filter((t) => t.phase === context.phase);
      if (phaseReqs.length > 0) {
        parts.push("", "### Requirements for Phase", ...phaseReqs.map((t) => `- ${t.requirement} (${t.status})`));
      }
    }

    const architecture = ciFiles.readArchitectureMd();
    if (architecture) {
      parts.push("", "### Architecture Boundaries", ...architecture.components.map((c) => `- ${c.name}: ${c.boundaries}`));
      parts.push("", "### Build Order", ...architecture.buildOrder.map((bo) => `${bo}`));
    }

    parts.push("", "## Specification", context.specification || "No specification provided");

    return parts.join("\n");
  }

  private executeMechanical(context: AgentContext, start: number): AgentResult {
    const ciFiles = new CIAgentFiles(context.project_path);
    ciFiles.ensureCIDir();

    const requirements = ciFiles.readRequirementsMd();
    const roadmap = ciFiles.readRoadmapMd();
    const architecture = ciFiles.readArchitectureMd();

    if (!requirements && !roadmap) {
      return {
        success: false,
        output: "Planning requires either .ciagent/REQUIREMENTS.md or .ciagent/ROADMAP.md. Initialize the project first.",
        artifacts_created: [],
        decisions: 0,
        escalations: 0,
        duration_ms: Date.now() - start,
        error: "No requirements or roadmap found for mechanical planning",
      };
    }

    let gitLogSummary = "";
    try {
      gitLogSummary = execSync("git log --max-count=20 --oneline", {
        cwd: context.project_path,
        encoding: "utf-8",
        stdio: ["pipe", "pipe", "pipe"],
      }).trim();
    } catch {
      gitLogSummary = "(no git history available)";
    }

    const phaseGoal = this.extractPhaseGoal(roadmap, context.phase);
    const phaseRequirements = this.extractPhaseRequirements(requirements, context.phase);
    const componentBoundaries = architecture ? architecture.components.map((c) => c.name) : [];

    const plans = this.buildPlans(phaseRequirements, componentBoundaries, context.phase);

    const planFileContent = this.formatPlanFile(context.phase, phaseGoal, plans);

    const planFilePath = path.join(context.project_path, ".ciagent", "PLAN.md");
    ensureDir(path.dirname(planFilePath));
    writeFile(planFilePath, planFileContent);

    const decisionCount = plans.length > 0 ? 1 : 0;

    if (this.shouldCommit(context)) {
      try {
        const commitMessage = CommitBuilder.buildTaskCommit({
          type: "docs",
          phase: context.phase,
          milestone: "v1.0",
          plan: "01",
          task: "01-01",
          subject: `create ${plans.length} phase plans`,
          status: "plan",
          decisions: decisionCount > 0 ? [{
            id: "D-001",
            decision: `Decomposed phase ${context.phase} into ${plans.length} vertical-slice plans`,
            rationale: "Requirements grouped by dependency analysis — independent requirements in wave 1, dependent in wave 2+",
            confidence: 0.75,
            alternatives: ["single monolithic plan", "per-requirement plans"],
          }] : undefined,
        });
        execSync(`git add -A && git commit -m "${commitMessage.replace(/"/g, '\\"')}" --allow-empty`, {
          cwd: context.project_path,
          stdio: "pipe",
        });
      } catch {
        this.warn("Plan commit failed");
      }
    }

    const waves = this.groupPlansByWave(plans);
    const plannerResult: PlannerResult = {
      success: true,
      planCount: plans.length,
      waves,
      decisions: decisionCount,
    };

    return {
      success: true,
      output: `Created ${plans.length} plan(s) across ${waves.length} wave(s) for phase ${context.phase}`,
      artifacts_created: [".ciagent/PLAN.md"],
      decisions: decisionCount,
      escalations: 0,
      duration_ms: Date.now() - start,
    };
  }

  private extractPhaseGoal(roadmap: RoadmapMd | null, phase: number): string {
    if (!roadmap) return "No roadmap available";
    const phaseEntry = roadmap.phases.find((p) => p.number === phase);
    if (phaseEntry) return `${phaseEntry.name}: ${phaseEntry.description}`;
    return `Phase ${phase} (no roadmap entry)`;
  }

  private extractPhaseRequirements(requirements: RequirementsMd | null, phase: number): Array<{ id: string; description: string; phase: number; status: string }> {
    if (!requirements) return [];
    return requirements.traceability
      .filter((t) => t.phase === phase)
      .map((t) => {
        let description = t.requirement;
        for (const cat of [...requirements.v1, ...requirements.v2]) {
          const item = cat.items.find((i) => i.id === t.requirement);
          if (item) {
            description = `${t.requirement}: ${item.description}`;
            break;
          }
        }
        return { id: t.requirement, description, phase: t.phase, status: t.status };
      });
  }

  private buildPlans(
    phaseRequirements: Array<{ id: string; description: string; phase: number; status: string }>,
    componentBoundaries: string[],
    phase: number
  ): PlanEntry[] {
    if (phaseRequirements.length === 0) {
      return [{
        name: `Phase ${phase} Core Implementation`,
        wave: 1,
        requirements: [],
        dependsOn: [],
        tasks: [`Implement phase ${phase} deliverables as specified in ROADMAP.md`],
        mustHaves: [`Phase ${phase} deliverables exist and pass verification`],
      }];
    }

    const independentReqs = phaseRequirements.filter((r) => r.status !== "blocked");
    const blockedReqs = phaseRequirements.filter((r) => r.status === "blocked");

    const plans: PlanEntry[] = [];

    if (independentReqs.length > 0) {
      const taskChunks = this.chunkByComponent(independentReqs, componentBoundaries);
      for (const chunk of taskChunks) {
        plans.push({
          name: this.inferPlanName(chunk, phase),
          wave: 1,
          requirements: chunk.map((r) => r.id),
          dependsOn: [],
          tasks: chunk.map((r) => {
            const desc = r.description.split(": ").slice(1).join(": ") || r.description;
            return desc !== r.id ? `Implement ${r.id}: ${desc}` : `Implement ${r.id}`;
          }),
          mustHaves: chunk.map((r) => `${r.id} implemented and testable`),
        });
      }
    }

    if (blockedReqs.length > 0) {
      const taskChunks = this.chunkByComponent(blockedReqs, componentBoundaries);
      for (const chunk of taskChunks) {
        plans.push({
          name: this.inferPlanName(chunk, phase),
          wave: plans.length > 0 ? Math.max(...plans.map((p) => p.wave)) + 1 : 2,
          requirements: chunk.map((r) => r.id),
          dependsOn: plans.slice(0, plans.length > 0 ? 1 : 0).map((p) => p.name),
          tasks: chunk.map((r) => {
            const desc = r.description.split(": ").slice(1).join(": ") || r.description;
            return desc !== r.id ? `Implement ${r.id}: ${desc}` : `Implement ${r.id}`;
          }),
          mustHaves: chunk.map((r) => `${r.id} implemented and testable`),
        });
      }
    }

    if (plans.length === 0) {
      plans.push({
        name: `Phase ${phase} Default`,
        wave: 1,
        requirements: [],
        dependsOn: [],
        tasks: [`Implement phase ${phase} deliverables`],
        mustHaves: [`Phase ${phase} deliverables pass verification`],
      });
    }

    return plans;
  }

  private chunkByComponent(
    reqs: Array<{ id: string; description: string; phase: number; status: string }>,
    _componentBoundaries: string[]
  ): Array<Array<{ id: string; description: string; phase: number; status: string }>> {
    if (reqs.length <= 3) return [reqs];
    const chunks: Array<Array<{ id: string; description: string; phase: number; status: string }>> = [];
    const chunkSize = Math.ceil(reqs.length / Math.ceil(reqs.length / 3));
    for (let i = 0; i < reqs.length; i += chunkSize) {
      chunks.push(reqs.slice(i, i + chunkSize));
    }
    return chunks;
  }

  private inferPlanName(chunk: Array<{ id: string; description: string; phase: number; status: string }>, phase: number): string {
    if (chunk.length === 1) return `Phase ${phase}: ${chunk[0].id}`;
    return `Phase ${phase}: ${chunk[0].id}–${chunk[chunk.length - 1].id}`;
  }

  private groupPlansByWave(plans: PlanEntry[]): { wave: number; plans: string[] }[] {
    const waveMap = new Map<number, string[]>();
    for (const plan of plans) {
      const existing = waveMap.get(plan.wave) || [];
      existing.push(plan.name);
      waveMap.set(plan.wave, existing);
    }
    return Array.from(waveMap.entries())
      .sort((a, b) => a[0] - b[0])
      .map(([wave, names]) => ({ wave, plans: names }));
  }

  private formatPlanFile(phase: number, phaseGoal: string, plans: PlanEntry[]): string {
    const lines: string[] = [
      `# Phase ${phase} Plan`,
      "",
      "## Phase Goal",
      phaseGoal,
      "",
      "## Plans",
      "",
    ];

    for (let i = 0; i < plans.length; i++) {
      const plan = plans[i];
      const planNum = i + 1;
      lines.push(`### Plan ${planNum}: ${plan.name}`);
      lines.push(`- Wave: ${plan.wave}`);
      if (plan.requirements.length > 0) {
        lines.push(`- Requirements: [${plan.requirements.join(", ")}]`);
      }
      if (plan.dependsOn.length > 0) {
        lines.push(`- Depends on: ${plan.dependsOn.join(", ")}`);
      }
      lines.push("- Tasks:");
      for (const task of plan.tasks) {
        lines.push(`  1. ${task}`);
      }
      lines.push("- Must-haves:");
      for (const mh of plan.mustHaves) {
        lines.push(`  - [x] ${mh}`);
      }
      lines.push("");
    }

    return lines.join("\n");
  }

  private shouldCommit(context: AgentContext): boolean {
    try {
      execSync("git rev-parse --is-inside-work-tree", {
        cwd: context.project_path,
        stdio: "pipe",
      });
      return true;
    } catch {
      return false;
    }
  }
}