import { describe, it, expect } from "vitest"
import * as fs from "fs"
import { parseIssue, validateStatusTransition } from "../../lib/issue"

describe("parseIssue", () => {
  it("parses all required fields", () => {
    const raw = fs.readFileSync("tests/_mocks/todo-basic.txt", "utf-8")
    const issueText = raw.split("Content-Type: application/issue")[1]
    const issue = parseIssue(issueText)

    expect(issue.id).toBe(1)
    expect(issue.type).toBe("feature")
    expect(issue.status).toBe("open")
    expect(issue.priority).toBe("high")
    expect(issue.description).toContain("Implement streaming JSON parser.")
  })

  it("parses empty relationships", () => {
    const raw = `
ID: 2
Type: bugfix
Title: T
Status: open
Priority: low
Created: 2026-02-01
Relationships:
Description: X
`
    const issue = parseIssue(raw)
    expect(issue.relationships).toEqual({})
  })
})

describe("validateStatusTransition", () => {
  it("allows valid transitions", () => {
    expect(validateStatusTransition("open", "in-progress")).toBeNull()
    expect(validateStatusTransition("open", "hold")).toBeNull()
    expect(validateStatusTransition("open", "cancelled")).toBeNull()
    expect(validateStatusTransition("in-progress", "done")).toBeNull()
    expect(validateStatusTransition("in-progress", "open")).toBeNull()
    expect(validateStatusTransition("done", "open")).toBeNull()
    expect(validateStatusTransition("cancelled", "open")).toBeNull()
    expect(validateStatusTransition("hold", "in-progress")).toBeNull()
  })

  it("rejects invalid transitions", () => {
    expect(validateStatusTransition("open", "done")).not.toBeNull()
    expect(validateStatusTransition("done", "in-progress")).not.toBeNull()
    expect(validateStatusTransition("done", "cancelled")).not.toBeNull()
    expect(validateStatusTransition("cancelled", "done")).not.toBeNull()
  })

  it("allows no-op (same status)", () => {
    expect(validateStatusTransition("open", "open")).toBeNull()
    expect(validateStatusTransition("done", "done")).toBeNull()
  })
})