Add API route for getting a user's bets

docs/docs/api.md

@@ -567,6 +567,54 @@ $ curl https://manifold.markets/api/v0/market/{marketId}/resolve -X POST \
                  ]}'
 ```
 
+### `GET /v0/user/[username]/bets`
+
+Gets a list of bets made by the user.
+
+Requires no authorization.
+
+- Example request
+  ```
+  https://manifold.markets/api/v0/user/ManifoldMarkets/bets
+  ```
+- Response type: A `Bet[]`.
+
+- <details><summary>Example response</summary><p>
+
+  ```json
+  [
+    {
+      "probAfter": 0.44418877319153904,
+      "shares": -645.8346334931828,
+      "outcome": "YES",
+      "contractId": "tgB1XmvFXZNhjr3xMNLp",
+      "sale": {
+        "betId": "RcOtarI3d1DUUTjiE0rx",
+        "amount": 474.9999999999998
+      },
+      "createdTime": 1644602886293,
+      "userId": "94YYTk1AFWfbWMpfYcvnnwI1veP2",
+      "probBefore": 0.7229189477449224,
+      "id": "x9eNmCaqQeXW8AgJ8Zmp",
+      "amount": -499.9999999999998
+    },
+    {
+      "probAfter": 0.9901970375647697,
+      "contractId": "zdeaYVAfHlo9jKzWh57J",
+      "outcome": "YES",
+      "amount": 1,
+      "id": "8PqxKYwXCcLYoXy2m2Nm",
+      "shares": 1.0049875638533763,
+      "userId": "94YYTk1AFWfbWMpfYcvnnwI1veP2",
+      "probBefore": 0.9900000000000001,
+      "createdTime": 1644705818872
+    }
+  ]
+  ```
+
+  </p>
+  </details>
+
 ## Changelog
 
 - 2022-06-08: Add paging to markets endpoint

web/pages/api/v0/user/[username]/bets/index.ts

@@ -0,0 +1,25 @@
+import { NextApiRequest, NextApiResponse } from 'next'
+import { applyCorsHeaders, CORS_UNRESTRICTED } from 'web/lib/api/cors'
+import { Bet, getUserBets } from 'web/lib/firebase/bets'
+import { getUserByUsername } from 'web/lib/firebase/users'
+import { ApiError } from '../../../_types'
+
+export default async function handler(
+  req: NextApiRequest,
+  res: NextApiResponse<Bet[] | ApiError>
+) {
+  await applyCorsHeaders(req, res, CORS_UNRESTRICTED)
+  const { username } = req.query
+
+  const user = await getUserByUsername(username as string)
+
+  if (!user) {
+    res.status(404).json({ error: 'User not found' })
+    return
+  }
+
+  const bets = await getUserBets(user.id, { includeRedemptions: false })
+
+  res.setHeader('Cache-Control', 'max-age=0')
+  return res.status(200).json(bets)
+}